What GT says is spot on with how to set it up. Also about the fuel injection with individual throttle bodies.
We went for the tripple webers for 2 reasons:
1. Efficiency of airflow (we don't care much about fuel consumption). The original manifold is designed to have a torquey mid-range to drag around a full size sedan. By replacing the manifold with the side drafts the airflow gets a straight shot at the inlet valve.
2. Cost. I bought a set of tripple 45mm webers (with hot 179 & M20) for $1200. I'd love to go efi with individual throttle bodies and aftermarket computer. The reality is that the efi computer would cost me probably $1200 alone, if not more.
Seriously for the street, have a look at Ed ma61's project. Don't run carbies. I only did it for the specific reasons above.