The R420.2 cast single plane intake was developed by Brett Miller and made in the US. The carb pad opening comes at a 5.250" square, unless 5.800 is selelcted. The ports will be cleaned up at a small size, unless custom port is selected, in which we will match the intake to your port and deck height. The chevy flange is meant to fit 5 degree face angle heads, and will be machined as tall as possible unless custom port is selected.