The oil pressure on a 73 307 V8 falls as you accelerate but increases when you let off the gas why?
Change the oil and filter. Install an AC/Delco filter and the correct amount of 10w30 oil. If the problem still presists, have an oil pressure test run. You may also have a defective oil pressure sending unit, loose wiring, or the wiring may be frayed and touching ground. Check the wiring throughly going to the oil pressure sending unit.