Carb Choosing

I need a new carb in my 66 F100 with a 351W. It has a Wieand Stealth intake manifold, Comp Cams Xtreme 4x4 cam (not a 4x4 or off road truck though), MSD pro billet dist. with the 6 box and timing control, headers with 2.5" exhaust and the bigger C9 heads that have been ported. the carb on it now is an Edelbrock. I dont like it and never have. It's the 500 cfm that was on my 302. I am wanting a Holley carb and thinking of the spreadbore because of the small primaries and big secondaries. What I need to know is which size carb you'd recommend with the little specs I just gave you? Someone told me 750 but that seems too big I would think.
Thanks for any help or information!

Ok thanks Denny, that is what I was thinking. Holley spreadbore I am thinking should be fine what are your oppinions on this? I will need the adapter plate for it but thats ok...

If I'm not mistaken, Holley only makes new spreadbores in the 4175 model. I'd go 650cfm, and vacuum secondaries on that. Also, the weiand intake looks to be a squarebore 4150-flange setup so you may go that way otherwise you'll lose power with an adapter (which you'll need to mount the spreadbore).