if you want to put a holley carb on the 4 barrel intake, you will need the carb spacer that holley makes. I porked up the top end of my '71 350 with a mild cam and I reworked the heads and I put a 4 barrel on and I even went to the trouble of putting a 60 lb. oil pressure spring in my oil pump. I only had 75,000 on it when I did it, and I wish I never had. Nothing but problems. It has severe blow by now, which is common because of the new components on the old block and such. I am in the process of building up a 455 with right around 450 hp. That will suite my needs.
