Don't own an A-Body (1969 RR), but go with the Centerforce. I made the mistake of buying a Zoom clutch for my "then" 450HP 451. The clutch burnt and smoked off the start, and was completely gone within 500 miles. Went with a single disc Centerforce DFX clutch (good for 650-700HP) and works perfectly with less pedal effort than the Zoom and is behind 600HP. You do get what you pay for when it comes to clutches. Purchased a Ram SFI Billet Steel flywheel as well along with the clutch, and everything so far has been great. While you're down their, you may want to replace your factory flywheel bolts with ARP units for additional strength if you haven't already. Hope I could help.