1978 Delta 88, Heater Core

Hey, what's goin on? Not much here. I have a 1978 Oldsmobile Delta 88 Royale with 126,000 miles. I read on an article somewhere else that if you switch the heater core coolant hoses, you can maybe get some of the grime out of the core and hoses. I tryed this, still didn't get any heat. I don't think there is a leak, because there is no dripping anywhere, and I took apart the whole a/c thingy, and there wasn't any leakage. After running the car for a while, I can feel like a 2 degree difference in the temperature. It's so small of a difference, i'm wondering if i'm just feeling things. Ha. Anyway, I was wondering how to get the heater core out. I didn't want to rip my car apart because I really didn't know what I was doing, so i'm waiting to see what info I can get. So, yeah. Also, can the gasket on the master cylinder affect the pressure for the brakes? I have to bleed my brakes first of all, because the brakes are spongy and to really stop that car from 50mph, it takes 2 pumps to stop. Not safe. Anyway, once I take care of that, that will be that problem. My other problem is I hear a umm. Sounds like hydraulics for an arm of a catepiller scoop. I'm wondering, would the gasket(has rust deposits around the lining, but is not breaking apart) just need to be cleaned, or would a new gasket be needed? I don't know if it's the gasket that's even making the noise. I should probably do this with 2 people. ANyway, if I could just get some direction, that would be awesome. Thanks!
Pint00 Hoffman