[JDSurge]

Hello everyone. I need some help with my oil pressure port. I have a rear seal leaking and didn't want to take out the transmission right now so I used some Lucas rear seal to fix it. At about the same time, my distributor when out (changed almost every part in it and still didn't fire) so I bought a MSD street fire distributor and it fired right up.
My question is: I now have no oil pressure reading on my new gauge. I removed the oil pressure sending unit at the same time I installed the MSD and there was no oil at the port or in the line. Could the rear seal stop leak have clogged up the oil port at the rear top of the engine, next to the distributor? Or do I have the distributor on wrong or bought a wrong distributor? The gauge was working before all this started but I was reading some threads about the ring around the distributor sending oil to the top end and now I'm wondering if I bought the right distributor.
I have a 350ci out of a 1977 blazer with HEI distributor.
Thanks for any advice to fix this.
JDSURGE
ALso posted a new pic of my blazer with the top off finally. Unfortunately, I went out to a Rod Run party last night and it rained in it for about 20 mins. I hope it will dry out OK.