I finally started the 340 in my 1969 Dart after a semi rebuild. I was only seeing about 15 psi cold at idle. Well after some thought and inspection I found the culprit. My own fault... I forgot to install the pipe plug that goes in the rear of the driver's side oil galley. This is the one you can see looking down the distributor mounting hole.
I really do not want to pull the intake back off to gain access to the area. I have made a couple attempts to install the plug through the distributor hole, but no luck so far.
I have heard that some have been able to reinstall that plug going through the distributor hole. I want to know what their method was.....

The only plug I know of back there is installed by taking out the transmission. Pipe threads most likely, and the plug should be installed properly, from the proper side, for the best fit and seal against leaks. Have fun.

A common L bend allen wrench with a flexible handle afixed to it might work so the handle would flex below the dist hole cuz an allen wrench needs a 60 sweep to get to the next "flat" on its 6 sides. Not sure if a person could rig up some kind of flexible "drilling" shaft like dentists' use so you could make that right angle turn to get it in. On a side note I drilled a 1/64" (.015") hole in an alum pipe plug (3/8 NPT) so the cam/intergear would get a constant stream of oil (tho you would think that area would be flooded with oil), one of my special internet tricks that ain't bit me in the a$$ yet (unlike the head gasket cooling holes). You will likely need to pull the intake (you may want to do the trans instead) as it is moderately tight access even with the intake off.

After a minor battle, I was able to get the oil galley plug in through the distributor hold. I had to rig up a tool by cutting a 1-5/8" piece off of a 5/16" allen wrench. Using and teflon tape, I secured the piece to 5/16" ratcheting box wrench. I put some teflon tape at the other end to secure the pipe plug to the allen shaft. I then used a large screw driver to apply forward pressure while turning the wrench.
I ended up with 80 psi using the priming drill. More that I thought that I would have being that the new pump that I put in was supposed to be high volume, but stock pressure.

Genius.

Oddly enough, I believe 5/16" is also the size of the oil priming rod.

Do you want to take the oil pan off after you drop several of those fittings into the motor trying to install them through the distributor hole If not, remove the intake now
Do that or the tranny and converter

Got to read his post and comprehend, he already got the plug in through the dist hole.

Good job rarefish.

(1) agreed! (2) it is

If it got away from me and I could not retrieve the plug or allen shank then I would be pulling the intake, but that did not happen. I got plug in fairly easy once the threads in-gauged.

I had heard that those ratcheting box end wrenches were pretty trick.

Good ending to a problem that could have been a [censored]. I like the way you approached the fix. The shortcut paid off, and had it dropped, then the long fix was in order. Might be your week to buy a lottery ticket.

Evidently we where both posting during the same time period, my reply was started before his second one was up and posted
I'm glad he figure out a way to get the job done