Generation IV Internal Engine - LS3 oil pressure problem

I have a ls3 in a 71 chevelle with a hummer oil pan. When i started up the motor for the first time everything was perfect, had oil pressure right away. After installing the motor i decided to cut the bottom of the hummer oil pan down because it hung to low so i trimmed the pan and the pickup tube. I then reinstalled everything and had no oil pressure so i pulled it all off agian to check the oring and it was ok so then it looked like my pickup was only a 1/8 inch above the bottom of my pan so i cut about a 1/4 inch off the the tube. I then reinstalled everything and first start up had oil pressure. I then let the car sit for 3 months and just started up the car and it has no oil pressure. My mechanical oil pressure is tapped above the filter and the line is clear. Ive cranked the motor over for multiple times for about 10 secs and no oil at all is coming up my oil line. I really dont wana pull it all out agian. Anyone have any suggestions?

It has to be something with your pickup tube. After three months it lost the prime. But that should fill up quick if everything is right. Try cranking without the spark plugs to get some revolutions on the motor. If that fails, take the pan off again. It's either the o-ring, or the pickup, one small pinhole in a weld will kill the suction.

Yea thisbis what im afraid of, everything looking good and then not knowing what to do.