I don't think you are asking a lot of a 445 and could get there without being too fancy
If you want to shoot for 116-118 trap speeds, I think you could live with 475 hp or so, and focus on suspension and driving to get the power to the ground
The parts you have, maybe even the cam too, could get you there with some significant head work (or better heads) and a good light valvetrain.
My opinion on carb, anything from 750-850 will work in this situation, IMHO bigger will be faster with the dual plane if you can tune it, but it is the least of my concerns at that level.