I think we've got it.
With approx. 3 threads showing above the main stud nut, I'm thinking of a short sleeve internally threaded and screwed onto the 3 threads of the stud.
Then enlarge the hole on the pickup bracket to fit over the sleeve followed by a short bolt on top of the sleeve to hold the bracket down. Thread lock should keep this in place...?
I should take pics.
PS. should the pipe threads on the pickup have any Teflon tape or similar before putting it into the oil pump? The plumber in me says yes but the old one had nothing.