I built a 402 SB with eddy heads, TTIs, 230@.050 hydraulic roller, and we ran a 650 double pumper, it was choking bad as the RPM climbed, started pulling vaccume and not pulling as hard as I thought it should. We had no room for a spacer and no bigger carb in the budget so I chucked a carbide in the router and milled out 3/4 inch of the divider from front to back and it would pull another 500 RPM. When we built it I did just a little radiusing in the plenum and some gasket matching... basic stuff. After eventually switching to a 750 it became a real animal pulling another 500 RPM more and now the hood and doors barely open and close (68 cuda).