[Big-Foot]

V-8 - You have a whole wagon load of troubles here.

With a 3500# car your 8" rear end will grenade very soon if you ever make all the HP your engine is capable of and you have tires that will put it to the ground.

With a 13.1:1 Compression ratio - you need 110 Octane gasoline.
A 30% (Thirty percent) by volume mixture of Tolulene is WAY too much. At the most you would run about 5%. It might bring you up to something that would approximate 110 Octane. The specific gravity of your octane booster is such that your jetting is way off the mark.

18 degrees initial advance is actually quite a bit.

The size of the carb has absolutely nothing to do with being lean in your case (or most others for that fact). It is most likely running lean because you have changed the fuel to the point of making it flow differently (different specific gravity).

You noted that you are running a 250 shot of nitrous with Alcohol - if you have ready access to volumes of Methanol - I would switch the fuel system over entirely to alcohol and run with it. We've fielded cars with 14:1 CR un-restricted with Alky with no problem. On the restrictor plate engines we have run as high as 15.5:1.

CFM - I would chose 830/850 CFM Holley.

Good luck!