Holley 750 (vacuum) or 650 double pumper or Thermoquad?

The Holley 3310-2 has the metering plate instead of the metering block. I also have a new Proform carb body for it. Am I wasting my time trying to drill the plate jet holes instead of buying a metering block with screw in jets. I have a buddy who has a large assortment of smaller drill bits. I'm on a really tight budget here. LOL

Also I was told that these bodies flow about 830 cfm and I'm thinking it might be too big for my set up even with a stiff secondary diaphram spring
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Here's the quick stats on my set up:

Completely stock 1992 360 Magnum with the exception of 340 exhaust manifolds, Hughes valve springs, MP Dizzy w/ orange box, cam 496/512lift 276/286 duration 110 centerline, 3.91 sure grip, 3000 stall converter, reverse manual valve body.

The other options are an off the shelf 650 double pumper and a Thermoquad off of a 76 400 cid also bone stock. I only have enough cash to make one a runner can't afford to build and experiment with all three.

Can't afford to experiment with all three, can afford to refurbish only one... would appreciate advice on which one to start with.....I'm really leaning towards the Thermoquad.