Taking the pan off will not assist you here. You will not get air to go through the rear cam bearing. So there are a couple of things you can try here. If you can, get yourself a spare distributor. Grind the pin off the gear, remove the gear, then remove all of the guts except the shaft and housing. Bring your motor up to TDC for No. 1. Remove the distributor. Disconnect the steel line behind the side cover at the top. Install your newly made tool, making sure the tang on the shaft engages the slot on the oil pump. Chuck an electric drill to it and spin the oil pump. You should get oil out of the top of the steel tube. If no, disconnect the bottom part of the tube and repeat. If no oil out of the rear cam bearing boss, then either the cam bearing was installed improperly or the wrong bearing was used, or maybe some junk in the main galley clogged it up. If you do get oil out of the top of the steel line, conncet it to the head. Spin it again. You should get oil to the rockers. If not, the passage in the head is clogged and needs to be cleaned out.
Here is the rub. It is possible to get the motor started and running without the tang on the end of the distributor engaging the oil pump. So, you will have to confirm that you got the tang into the oil pump slot when it was installed. That very well may be the issue, no oil pressure at all.
If the distributor tang is engaged to the pump and still no oil at all, then you will have to go to plan B.
Plan B, either install a T at the back of the block and run a small diameter copper line from the T, around the back of the head and along the pass side of the head to where there is a little hex plug on the side of the head. Install the appropriate fittings and plug the line into the head for oiling to the rockers. The aftermarket used to sell kits for this purpose (clogged steel line) and they turn up on ebay every once in a while. As noted above, bigger is not better here. To large an id on the line will bleed all the pressure and starve the motor (main and rod bearings for example).
Plan B.1, Run the copper line from the out put of the oil filter to the side of the head. The oil filter just dumps the oil directly into the pan anyhow where it is instantly diluted with dirty oil. Now you will have clean oil to the rockers. Just make sure you don't have too much oil to the rockers. Again, more is not better. The rockers should not be spitting oil out. They should be dribbling. Dribbling oil to the rocker tip and push rod cup, and over the spring to cool it. If spitting, its spitting onto the inside of the valve cover and not lubricating like it should.
My vote, Plan C, take the motor apart and see what the culprit is and fix it.
