The first one I ran was on a 14.5comp, w5, 408ci, R block. The one I am currently running is a 360-1rp, 433ci, R3 combo. Neither want to pull into the 6,500 on up rpm much, both have or had large rollers and proper springs and such, current combo runs best shifted at 6,200. Nothing is the same on either motor besides the intake.