602 (Legal by Yellow GM book) Crate engines may run a Holley 650 or 750 Carburetor with stock size base plate using straight through holes no larger than stock. CARB. SPACER PLATES (2/3/21) CVC products no longer makes the 1.688 billet spacer plates so effective immediately the Moroso pt #64991 4 hole billet aluminum Max. 1” thick spacer with Max. 1.696 holes is approved for use in competition