Hi there
Just to bump this I found a picture on wikipedia (on another computer) that showed nut, TO-3, mica gasket, mounting surface, plug, washer, soldering attachment (eg a ring terminal) screw
I was going to go screw, inslating plug, washer, ring terminal, TO-3 package, mica layer, mounting, nut
That way the screw was insulated
Is there a reason not to?
I hope this makes sense - I've described the situation from top to bottom. In the "wikipedia picture" the screw conducts and is insulated from the board, in what I was going to do the screw's insulated