The Melling M-45 pump fits all 235 and 261 engines, and with a little tweaking of the plumbing it might work on a 216. There are usually several M-45's on Ebay at reasonable prices. I'm working on an adapter to fit the oil pump for a 250 or 292 Chevy six to the early stovebolt engine- - - -it has bigger gears and more volume than any of the original equipment pumps.
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!