Question about carbs for tunnel rams

I've been using a tunnel ram on a 496 big block.Started with 2 -550 CFM Carters. Then switched to a pair of Holley 750 Dbl pumpers. Ran a little faster but not much. Actually ran .2 sec quicker with an M 1 intake and a 1050 Dominator. Best carbs are prob a pair of 660 center squirters. They are made for the tunnel ram set up. What carbs are you running? Post a better pic of the carbs, that would be helpful.
I actually dont have carbs for it yet, the pic is from previous owner, i was told perhaps a pair of holley 390's would be ok due to my engine being only mild