Quote:

Gold,
The outer diameter is definitely a countersink that leads
Down into the hole. The second picture, left side
Is my best shot of the c'sink.
Is this an issue? If so, can I use a soft washers help
Seal it?
The second picture makes it appear that I can see down past the hex of the plug. This might just be a optical allusion.

Looks like you need a tapered seat plug,no gasket needed or wanted in that application. My memory might be fuzzy as it's been years since I built anything with a J type head but I thought they used a gasket type plug??? I'm guessing you need a 3/4" reach tapered seat plug?? I'll do a little research and hopefully someone will come along and give us a hand.LOL