What is your budget?
My humble opinions...
The cheapest conversion is a Chevy 350 V8. That was my original intention, then I thought about all the other options.... A six is nice, I thought about rotary for a while, entertained a few other ideas, but always come back to the 350. Although I have to say, Scott's Suby is sweet... a WRX motor is the only option that could sway me from a SBC today.
1. Extreme Raby motor; SWEET, simple plug and play, but dang it I can't afford it.
2. Chevy 350; Most power and torque for the buck hands down. No limits. Easiest build and conversion due to so much aftermarket support. A 300HP V8 will run reliably for a lot of miles. Cheapest rebuild.
3. Subaru WRX motor; Modern boxer, can put cooling system in engine bay.
4. Porsche Six; Cool... it's a Porsche... and it sounds like one.
5. Rotary; Small and light, can get strong HP... but not as much torque... Could physically fit cooling system in engine bay pretty easy but they run so hot that might not work.
(Fortunately, my 2.0 with minor mods is running strong enough to satisfy me until I get everything I need for the swap.)
