Drivers side Oil Galley Plug missing....installation in car possible???

I ended up doing this on my dads 360 in his express. I dissassembled the engine had machine shop fo the work, and i reassembled it. I put all the plugs back in that i took out. Machinest found the one i missed and took it out. Never told me. I put it back together and it had the pumping down clattering lifters. I pulled the distributor and looked in with a mirror and found the open threaded hole. I was pissed. I stuck a shop rag down in the hole to prevent the plug from falling somewhere where it wasnt supposed to go, then i cut an allen key fairly short, and carefully got it started thru the distributor hole and tightened it up. Pulled out the shop rag, and stuck the distributor back in. I will never make that mistake again