Engine swap

I strongly advise against that. Of course you will have computer issues. You have an operating system for a six cylinder. You will have suspension problems, wiring harness problems, exhaust problems, cooling system problems, all far more technical than you are prepared to deal with.
If you want a 454 truck, I suggest you find one already equipped.

You will find that the headaches of attempting this could far exceed the cost of finding another truck. Not to mention that it is totally against Federal law to do that. That is considered emissions tampering.

Hi guys. What I would like to add to brother Wrenchtech's first reply is, "I really strongly advise against that". He hit the important parts, but in addition, the proportioning valve in the brake system's combination valve, and the diameter of the rear wheel cylinders are part of the design of the brake system that affects front-to-rear brake balance. You are going to need more pedal pressure to stop the truck, and that will result in easy rear-wheel lockup.

The front springs are designed to hold the weight of the front of the truck. They can be different for as little as with or without the added weight of air conditioning, and they will be different for a heavier engine. Besides just being level, they have to handle the weight transfer to the front springs when braking.

Another thing to consider is lawyers and insurance investigators love to find these kinds of modifications, and they really love raised trucks and lowered cars. They will convince a jury that you were partly at fault for the crash when their client ran the red light, because you were less able to avoid it, and they will be right. I have written entire novels on how these alterations adversely affect braking distance, steering response, handling, comfort, and tire wear.

You will also have to put in more effort at times when selecting replacement parts. GM used to be famous, I think, for using the same ears on the frame for the engine mounts for any engine, but if you say they are different, if you need a new mount, do you buy one for the engine or for the frame? That is the kind of thing I am referring to.

Also, consider the fuel mileage. You might consider test-driving a 2014 Dodge 1500 with the 5.7L Hemi. I bought a smashed one two years ago, then my friend rebuilt it in his body shop. For just under $21,000.00, I have a truck with 4,200 miles that will tear the hitch off my trailer, ... And unloaded, it gets 28 mpg. I hate the business practices of GM, but if you are in love with other brands, I am sure they have trucks just as powerful. Think of all the time you will save, and everything will be put together right and will be matched for best possible performance.

Wrenchtech says, "I suggest you find one already equipped". I say, use this as an opportunity to buy what you want. Use the money you save on gas for your torch, that which is wasted on trial and error parts that get thrown in the corner, and the hours and hours and hours you could have been doing something fun with the girl next door!