This is all good information, I am leaning towards the Scat brand at this time since I have heard more good information about them. I am sure that it goes without saying you can always get a bad part and proper installation has everything to do with the final product, (something I relearned the hard way). What about heads? Should I rebuild a set of Vortec heads (they are cast iron) that I have or should I buy special performance heads. Remember this engine will probably be all off road use.