I have built a few race cars, so the engine 'conversion' task is not new to me.
The biggest lesson is to find people that worked with your engine and technology before. I use Corvette spline and bearing hubs on my Honda axles, because, I know these parts.
1. I bought an assembled motor from a reputable shop. I bought it from a customer that never used it. However, I talked to the shop, got the build sheet and got references.
2. I found reputable sources of aftermarket parts. This came from Honda forums k20a.org.
3. I found a local tuner and watched him tune a similar set-up, before I let him touch mine.
I cannot over-emphasize (1). I had to replace cams and thought that I should be able to handle the timing. Bent 2 valves!
Whenever, you undertake such complex projects some problems are to be expected.
I had a bad MAP sensor. It was brand new. The car would almost start i.e. catch, then moment ECU went into its standard mode, it would say MAP=0 so fuel =0 and stop. Took me a day to figure it out. I cannot build a motor, but I am good at diagnostics.
This is painful!!!
"Pain Makes Man Think
Thinking Makes Man Wise
Wisdom Makes Life Endurable"