??Distributor shaft depth in oil pump drive??

The bushing can be shimmed before it is installed and usually will be checked by the builder if gear alignment is off. That will lift the gear. That said after installing many distributors. Not many drop down more than that on a original motor due to bushing surface wear from the cam pushing down

. If its a new build correct the problem while it's apart. Make sure you hone the bushing to size for oil clearance. If it is to tight it may spin in the block when it initially gets hot for the first time.