This
oil galley plug is critical, as you can see there are few threads to seat a plug, a conventional allen head pipe plug will seat deep enough to block a large percentage of the
oil flow to the engine, not something you want after all the oiling mods!.
This is easy to see when assembling engine, turn engine up on it's left side and look in the top
oil inlet hole, where the oil filter/adapter bolts to the engine.
I turned down the plug on my lathe but, wound up cutting to much and got into the allen socket.
After some searching, I located and used a brass 9/16 hex head pipe plug, after turning it down in the lathe.
Remember, there are only 4-6 threads
in the block so don't torque the plug to much and of course us a good sealer.