I make a hold down clamp from 3/8" X 2" aluminum flat stock with a hole to bolt it to the block, and a slot with a pinch bolt to turn the housing for timing adjustment. I think I've got one stashed away that's on a modified distributor housing. If I can find it, I'll post some pictures. If you fish for big catfish in swift water, aftermarket distributors make good weights to keep your bait from drifting away.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!