I have an 800 cfm carb on my 464 ci, it's large enough.
I have my timing at 29 max. I got best power and torque on the dyno at 29. I also blocked off the vacuum advance as I was getting light detonation at part throttle pulls, none at WOT. I welded the low side advance slots in the distributor to keep the timing from going below 18 at idle. That gives me a cooler idle and have plenty of advance from idle to 3200 rpm.