Engine replacement compatibility?

Well, it's kind of a long story. So not too long ago the weather got freezing cold and I had straight water as coolant because I had a small leak in the radiator and wasn't about to keep buying coolant. Well needless to say everything completely froze and about 4 freeze plugs popped out. Well after I thought everything was defrosted, I started it up and it made a loud winning noise which I believed came from the water pump because after running for a minute I heard water start pouring out from somewhere, so I immediately shut it off. I took the water pump off and everything seemed fine with it, so I put it all together and that's when I realized the freeze plugs that popped out. So, I put them all back in correctly and it didn't leak anymore. So, I put actual coolant in it and gave it a few test runs and everything seemed fine. So, I got ready and headed to town and after I got to town, I started noticing more and more Power lose and the sound as if I was completely missing a spark plug, and then noticed my check engine light started flashing. So, I pulled over and took off the oil cap and noticed milky stuff on the underside of the cap. I then removed one of the coil packs and seen milky on it also. So, I then just assumed the head gasket blew. So, I got it towed home and seen that all the coil packs and spark plugs were covered in milky stuff. Which I thought was weird because none of the gaskets were bad the prevented oil from even getting to that area. So, idk how it was even in there. So, I ordered now head gaskets, torqued everything down exactly how it's supposed to be and drained the oil from the pan and as soon as the bolt came out just maybe a cup of pure water shot out and following that was oil that was just a little bit contaminated with water. So, I put new oil in and was about to do the process of cleaning out all the milky inside the motor and when I started it, milky stuff started coming all around the edges where the head meets the block, fast. So that's when I said screw it and haven't touched the car again. Now trying to find a motor to put in it that I can afford. And to answer your question, idk exactly how many miles is on that motor because that's already the 2nd engine I had to put in it that I got from a U Pull It, if you know what that is, it's like a junkyard and there was no way to see how many miles where on it. But the dash shows about 250,000, which I know is a lot, but I take care of my vehicles and change gaskets and oil as I should, and I just replaced all kinds of stuff. But yeah, I still have no idea to what exactly happened. Only thing I could think of is I cracked the block of the heads off something when I started it and it wasn't completely defrosted. But I was wondering if the engine cracked somewhere, it should've been leaking or showing signs that it was way before I got to town which is about 45 to an hour sway from where I live so I still don't know.

Cracked the block or the heads or something***

Also, I did find at U Pull It a 2008 kia rondo and it had the exact same 2.7l as mine but it didn't look too promising from the condition it was in.

Well, it was coming from all around it from what I could see. For sure from the front side that faces me from one end to the other and yes coolant was definitely still mixing because I put fresh oil in and coolant and there was just a pool of it underneath my car after I started it up. And honestly it actually seemed pretty cleaned from what I could see through the oil fill cap and they charge $250.00 which is the cheapest I'll find one I'm almost guaranteed lol and maybe if I brought a battery out on the yard if that's not against their policy maybe I can connect it and get some info on the milage. I'm going to go back out there tomorrow (Monday) morning and see what I can do. I mean after thinking about it I have a lot of new parts and sensors that are in better condition, maybe I can just rob the old motor and put it all on this motor and have a decent vehicle again. But I am going to try to get the mileage checked tomorrow for sure if it's possible. Do you know how difficult it would be for me to put a 3.3l in as long as I put the transmission and the computer and all the suspension components that make it AWD, is there anything else that I would have to change? I've tried searching for am answer for that question for the longest and never get anywhere so hopefully you can give me a promising answer lol. And I appreciate the help a lot. Thank you

Are you talking about the motor from u pull it? If so, I put a wrench on it and it does turn. If you're talking about the motor that I'm currently trying to replace then yeah it'll fire right up right now with no problem at all lol and okay, never mind on that last question about the 2wd to awd lol I mean honestly it wouldn't be too expensive to do considering I have every single part I need to do the conversion sitting at u pull it for fairly decent prices. Or are you insinuating it's a lot of stuff to do? Lol

I don't believe the key was even in the ignition put at u pull it if that's the one you are talking about.

Okay, so you do believe my current engine is cracked somewhere? Going off of what I described to you.

Yeah, I was told I should be able to see the crack, but I had seen nothing, I had the heads completely off, cleaned up all good and everything. Only thing I could think of is (if it's possible) it's a small hair line crack not easily/if even at all viewable.

No, I haven't but it's cool I went and pulled a 2.7l from a 2008 model from out of town today. I shouldn't have to get the computer from the 2008 should I? My 2007 computer should work, right?