My Mk3 had a 306 with AFR 165 heads, RPM Air Gap intake, MSD distributor and box, COMP Cams 35-440-8 Magnum hydraulic roller camshaft (similar to yours but a little less lift) and it ran fantastic on a Quick Fuel SS-650 carb. I don't own it now, but the new owner reports it's still running great. I do not think the SS-650 is too big for your engine. Like all carbs, it needs to be tuned. But should be a good match for your engine.

I have the -AN (annular ring) version on my Mk4 #7750. Wayne Pressley recommends them. First I've heard it reduces the cfm. Real happy with that one too. That engine is a DART 347 with bigger heads and a little more cam. I have the 750 version on that engine. Probably a little big. But it's wideband tuned and hits all the numbers. Runs really great as well.

I don't think you'd go wrong with either version.