Will this combo run on 91?

Yes in a vehicle less than 4,000 pounds but 93 would be more safe and may allow 38 degrees total timing that those heads will like over your stated 35 degrees.

Muddy557 wrote:

Be sure to keep the engine temperature on the low side ... 160 degrees; 180 degrees max.

BBFTorino wrote:What size is this motor? 557?

Pistons show 3.85" stroke

.040 over 460, roughly a 468

BBFTorino wrote:What size is this motor? 557?

I have a very similar combo to you. My d0ve heads are milled down to 66cc so compression should be similar and my cam is 251/260 .606-.632 108ls solid flat tappet. My trucks 4100lbs and I run it on 93 with 40* timing

Thanks for the replies guys , does anyone have a rough guess what the comp ratio would be with a set of d3’s instead of the doves ?

8.48/1 assuming 95cc on the D3's

http://www.wallaceracing.com/cr_test2.php

I started with your claimed 10.125/1 compression and only changed the head cc's.