I have 89 with a 91HO in it. I have a HV oil pump pressure is about 58 to 62lbs cold idle and about 45lbs warm. Pressure is about 60lbs at cruising speed. Had to change a distributor gear cause it was almost completely wore down. I thinking i might have some camshaft walk. Does anybody have any experience with this? Should I change my oil pump?, run different oil weight? Or maybe different spring in cam button? Any help is appreciated. Thanks.