I run almost the same set up with an automatic. I run a edelbrock RPM airgap to help with the heavy car. I also run a 750 double pumper that was worked by the carb shop to flow 830cfm. It likes more carb
and I have run a regular 850 on it. It really likes the more top end air but I have trouble getting it to idle very well with that 850. The air gap seems to run well with it I shift at 6 or 6200. My 68 cuda runs 7.01 at 96.5 in the 8th.