Porting BB heads

Use the 346s. They have a better bowl area and exh shape than the 906s. As for what to do. You can do most of the template work by having teh valve job done by a shop that uses cutters, not stones for the seats, and have them do a 5 angle valve job on them. Then just blend the throat cut (the steepest angle and the one that tapers into the rough casting) into the port about an inch. After that, gasket match the intake port, and do not gasket match the exh side. The trick on the exh side is to keep the port as small as you can while making the 90° turn the gasses have to take gradual and smooth. Watch out, there's water in the tops of the exh ports so dont raise them much, just smooth out the top of the bump, and smooth out and minimize the exh guide area. What you DONT want to do is remove much from the short side of the exh or intake. Smoothing, ok. But no re-shaping. Amatuers make the most mistakes by thinking bigger is good and bigger than that is awesome. That's what trashes the flow at low and mid lifts and the low and mid are where the power's at.