It sounds like you have aoil pressure problem that needs fixing right now, don't run the motor any more until you get it fixed Are those Comp Cams solid roller lifters a straight body or do they have a machined band in the middle of them? If machined try pulling the distributor and oil pump drive and use a priming rod and drill motor to prime the motor, I would remove all the spark plugs to make turning the motor over easier and the plumb a mechanical oil pressure gauge where you can watch it and slowly turn the motor over by hand (get a helper if needed ) while priming it. If it gets better and then worst oil pressure while rotating the motor the lifters are probally the cause Let us know what you find please, it will help others on here later