Well, depending on the engine, its not just going to be 5k for it...
A LS1 + tranny will run you 6k. Then you have to get all the measurements on the engine bay done, assuming it would fit. Then you'd have to get everything custom welded, new mounts fabricated, new axels, a completely NEW suspension.
You'd be looking at a good 4-5k just to prep the car for a engine like that. This also doesn't mention the time it would take and all the parts you would have to fabricate (custom dash, ect...)
Its not worth it.