I have an 88 350 tpi, at idle it only has 10 - 15 lbs of oil pressure(just over the red line), at 300 rpm i have maybe 30 lbs. I changed the sending unit on the manifold and there was no change. Is the pressure too low? what should i do next?

 

Verify the presure with a mechanical gauge. You can temprarily connect one at several places, and the rear ledge is not one of my first choices since it is somewhat inaccessible.