[ItBites]

Get one of the many Holley clones instead of the Holley. Speed Demon is likely OK. The clones are actually improved over the original.

As far as carb size goes: I posted a whole dissertation on manifold pressure as a function of carb restriction in another thread and if I knew how, I'd direct you there, but:

Ford uses a 1050 or so because that is what the motor wants in order to make the best power (they can advertise big numbers that way). Driveability is somewhat sacrificed. Warm-up or whatever you're worried about is not the issue. The issue is signal from the cylinder to the booster venturi that draws fuel from the bowl. with a larger carb, the manifold pressure is closer to atmospheric and therefore the resolution of the signal is not as high fidelity as with a smaller carb. This is only an issue during transition from low to high throttle positions(Throttle response).

On the other side, with a small carb (and 850 is small for a racing engine of that size), the manifold pressure will always be somwhat low, even at full throttle, and resultingly the charge density into the cylinder will also be low, reducing power.

For power, you want a high density charge in the cylinder (more air and fuel = more power). For response you want better manifold vacuum.

Everything is a compromise. I'd go with the 1050 from BG or Speed Demon or someone that builds a good carb and with a light car and big engine, the throttle response issue will be hardly noticeable.

BTW, don't even bother with vac secondaries, that big mill will pull right thru any hole a vacuum sec is designed to fill.

OR do like I did and go injected and forget about vacuum signal required to pull fuel from a bowl - how primitive...