low oil pressure to new engine?

well, Im now starting to really think that I have low oil pressure...I havent found a mechanic with a mechanical oil pressure gauge .. Ive tried two...



driving around and looking is kinda 'counter intuitive' to the possible problems I might have. i.e. if I do have low oil pressure then driving wont be helping it...



Ive replaced everything from the sending unit back to the gauge, including the gauge...



the gauge shows full/regular pressure until it gets 'close' to normal temperature... once it gets to regular temperature, the pressure slowly drops to nothing... revving will slightly increase the pressure, maybe up to the first tic mark. but no where close to normal.



the motor is sounding more 'mechanical'... I have really bad hearing, but if I open the hood and listen, I can hear a lot of 'noise'...



I read another thread that said it maybe main or cam bearing, or oil pump.



is there a way to determine/isolate the pump to test it?



is it worth while to just rebuild the motor instead of spending money on pulling the oil pan, and replacing the oil pump. Im guessing that project, will cost me about $350-500 ????



I can't do it.. I might know how, but my body wont let me get under the jeep ...



should I use that 300-500 for the rebuild or for a new motor?



should i rebuild the motor or should I get a different motor?? different as in a chevy or something else...