i think that having the engine sitting and everything cut is more then 20% but its ok
I'm speaking from limited experience; I've only done the swap five times.
I might be a slow worker, but the kits took me about 40 hours to build from scratch. You get a 40 hour head start by buying the kit compared to building the whole thing from stock materials, so I am not counting that 40 hours toward build time.
Let's say that there's 10 hours in cutting the body and removing original spot welded fixtures to a point at which you can bolt the engine into place. Heck, let's say that you spend 20 hours doing that work.
Still ahead of you is:
40-60 hours of cutting, trimming, and welding up all of the reinforcements and replacement panels;
20-40 hours of finishing and painting the engine bay;
40 hours of integration of K20 wiring harness and fixing whatever delights you find in the FIAT wiring along the way;
5-10 hours integrating cooling systems together to do a neat job of it;
10 hours removing, rebuilding, modifying, and reinstalling pedal box (you'd be crazy to do this swap without performing this maintenance);
10 hours modifying Chinesium header to fit plus building exhaust;
5-10 hours integrating fuel systems and cleaning up the fuel tank;
5-10 hours putting the interior back together, depending on how far it was taken apart for the swap;
10 hours of recovering the tool that you just had five seconds ago.
I might be a slow worker. OK, I *am* a slow worker. I prefer the term "methodical," but that's just me. Matt's goal for me to build a K20 conversion from start to finish was 150 hours. I never once met that goal. I was closer to 200-250, depending on what had to be done (every car is different, and every conversion is different in some way.) I have no doubt that a faster worker can actually do it in 150 hours, especially if he is not as thorough and meticulous as I am, but is the home hobbyist going to be faster? I think that the typical hobbyist working in his home garage will spend 300+ hours performing the swap to completion. And that's really not a terrible amount of time. It's work that we enjoy on a car that we care for. But it *is* going to take time, and getting the body cut to fit the engine is just the start.
Now, with all of that said, $12k seems like a fair deal assuming that the engine build was done correctly. It's a solid roller with a lot of expensive parts. I think the problem is that most X owners need to chip away at that $12k rather than spend it all at once. For most of us, it would be better to spend $16k spread across two years than to spend $12k in one shot.
Selling a built K20 by itself opens you up to a much broader market. Same with the trans.