This is what I found from my preliminary research. Please correct me if I have something wrong.
So far for me the best engine is the LS1 from the late model Camaro/Firebird Fbody. It will keep the car street legal and allow you to keep some of the emissions stuff. How much I don't know since I need to dig more into it.
You can get good, usable drivetrains for under $5k. What I was going to do is just get a shortblock and have a shop do a mild rebuild for reliability. From what I found, the bottom end is pretty solid if all you want is 300 bhp. Maybe get some goodies from ARP to reinforce it a little more, and definitely a better oil system (dry sump of some sort) for roadracing.
I figure mid teens for the Hinson kit. I'm going to go ahead and allow some more budget for some final installation and fabrication if necessary.
The only thing I don't know about is the driveshaft and rear end, but I'm sure I'll figure it out once I get in touch with the folks at Hinsons.
So right now I'm looking at a conservative estimate of about low teens for a turnkey setup. This will allow me to attend a full season of roadracing without a rebuild (I hope), and I'm hoping it will be easier to find parts to feed the motor.
At least I can sell my SR to help fund some of it. Bye bye turbo. Hello V8
