A few points as I have a 505 that gets driven and raced frequently...

We run an 850 Demon carb. It seems to do everything well and zero issues since installing in 2016.

The 8 3/4 is short-lived in an application like this. I would highly recommend upgrading to a Dana 60 or 9 inch.

Don't overcam and don't overgear. These make huge torque so all that isn't needed. A mild hydraulic roller and 3.54 gear works fine.

Put a good set of drag radial style tires on it. A regular 400 treadwear tire is like driving on ice with these.

My car is 3,700 lbs. across the scales and does really low 11's on motor alone with pump gas and mufflers. It has a Holley Street Dominator intake that probably costs me some power but fits under a stock flat hood.