strtolds

HEY FELLAS, I've recently rebuilt a '74 olds 350 and cannot get good oil pressure. I checked the main clearances during assemby and all tolerances were within spec. I replaced stock type oil pump with h/v pump and this seems to have lowered the oil pr. I've used different gauges for readings and all read the same. I'm getting 8-10 psi at idle (750 rpm) and no more than 22 psi as rpm climbs. I've done everything I know to do and am getting nowhere. I am a big chevy fan but this is my first olds project and am hoping you can tell me what I've missed! Thanks for any help I can get!