Did u use way too much assembly lube? I could see that clogging up your oil journals if you have too much. Also with the valve covers off and the engine on, go one by one. Loosen a rocker arm bolt until it begins to tick then slowly tighten it until it stops ticking then you be the judge, a 1/4 turn more or a 1/2 turn more. Once thats finished your valves should be properly adjusted.
If ur noy getting any oil pressure make sure your oil pump is working properly also. Do not make a costly mistake . Infact while ur doin the valves make sure oil is getting to the top ( you'll see it, itll be every where)
Could be a faulty guage.
95 T/A , M6 , Lt4 hotcam , 1.6 RR, Trickflow aluminum heads, Moroso CAI, Polished Elbow, 58 MM Holley TB, 44 pound Injectors, Edelbrock RPM air gap Intake, MSD wires, MSD opti, Pacesetter LTs, Spiral Bullet, Magnaflow catback, 4.10 gears, Aluminum Driveshaft.
93 Corvette Spec Flywheel