Guys,
This is where I am. I'm putting together (well, not me, my builder) a full roller, windsor based 393 able to spin up to 7200-7400 rpm, running something like 11-11.25:1 CR, AFR 205 Heads with some porting, a weber intake, and as aggressive a cam as I can get away with and still be sort of streetable (I don't know the exact specs, but I'm willing to put up with a lot, and will track the car).
As you probably know, flow in 48mm webers is limited by the venturi (choke), which comes stock at 44mm. You can put in 45 mm venturis without any machine work, and can put in 51.5 mm venturis with some work and parts at a cost of about $800 each (in addition to the cost of the carb). At that point, you're getting close to the cost of new aftermarket weber copies (EMPI) which can be produced in 58-60mm versions. The VW bug drag racers use these frequently.
If you look at the graph (Ron) provided, standard 48mm Webers won't really flow enough to make the most out of my engine's potential at the top end. The intake isn't the issue, and will flow plenty and fit right up to the 58mm versions. From what I've found, the general consensus is that 48s can only flow enough to make 550-600 bhp (depending on who you believe), and my motor could potentially do a bit better than that.
I'm certainly open to everyone's input, as my personal motor-building experience is not with american V8s.
Thanks for your input!