Supercuda's on the way back...after18 years!

More Trouble!!

So we are getting the engine ready to fire. Fill up with break-in oil , use a drill to prime the oil pump and check circulation. A quick look under the car and....Oil everywhere!! No obvious signs of a leak point but oil is pouring out of the back of the engine between the block and the bell housing. We have no choice but to remove the transmission and find a screw in dowel missing from the back of the engine . Fu%K ! Fu%k Fu%K !!! Stupid mistake again by me.
The only reason for this post is to make sure I haven't missed something else. The top of my Magnum 360 is typical Edlebrock heads/Airgap Performer intake /full roller cam/front of engine switched to LA style timing cover, pulleys etc.. I

Is there any reason this dowel is not installed? This engine was professionally built by a well known Canadian Engine builder who specializes in Mopar engines.

Thanks for any help with this.
Don't worry, you're engine builder was serious and cleaned the oil gallery, unfortunately he forgot the plug. there are some freezer plugs too in the back. I prime my engines on the engine stand, measure the pressure with Ohm Meter on the original pressure switch or a gauge. I would fill the engine coolant with a vacuum cooling system filler, it's perfect clean, you're new engine has no air bubbles in the cooling system.
Good luck and enjoy the first run!