high oil pressure

I picked p a 76 Volare 318 car, runs drives although I am yet to run down the road. Just got the leaking brake line repaired. The PO had recently put a "gauge type" oil sender on it, and I hooked up an aftermarket gage to it. I admit I always bypass the idiot light and install a mechanical gauge, but after triple bypass and getting too the age of 71, blood thinner, and bruising like a baby peach, I really did not want to pull the dist., and deal with it all!
I figure the oil pump relief spring is maybe stuck, question is, anyway for me to diagnose this other than hook up mechanical gauge??? It shows 100 pound cold!