Crate Motor

What years are you considering? Why are you wanting to swap in a crate motor?

I would think in the price range you're talking, you're going to get a pre-2010 car; would imagine a Coyote swap (assume that's the 5.0 you mean) would be very complicated.

V6 car would matter, as IIRC the rear-end isn't the 8.8 like the V8 cars.

If you're trying to do this to have a cheap way to get a late model 5.0 car, you're not going to save much money, IMHO, and you're going to have an oddball that will require more than average DIY skills to build and maintain. No offense, but my guess would be since you had to ask the question, you'd probably be in over your head.

If you get lets say an 05 GT, a 5.0L swap would not be difficult. You can get a complete 5.0L production motor from FRPP and the wriring harness to run it. The 5.0 will bolt onto the factory 3560 5spd in the GT so it would be a relativly easy swap as swaps go. You will need to shop around for an aftermarket return style fuel system to run that set up, the fuel pump for the 05-10 3v GT's can handle 450 BHP but if you're going to buy a fuel system anyway a pump upgrade wouldn't be a bad idea. Another choice would be to find an 11+ vehicle that has been wrecked and swap over the parts from that car.

If you got a high mileage V6 and just swapped in the powertrain, you are still left with the 7.5" rear end, the stock suspension, undersize brakes, no exhaust, and an interior and paint from a high mileage car. The power steering system would also have to be replaced, the 5.0 cars are all electric power steering. In the end, unless you are building a track car where those parts would all be replaced anyways, you are looking at a ton of work and money. You would probably be better off buying a used 2011 car that comes with everything you need. The 2011+ car would have a much higher resale value as well, most people would not pay much for an engine swap car.