Once I discovered the threading tap trick, all the other options got abandoned. I believe it's a 5/8" thread that works right on a stovebolt bushing. Round the end of the tap with a bench grinder to keep any sharp edges from digging into the nottom of the counterbore in the crankshaft. That doesn't prevent the tap from working for it's original purpose of cutting threads, as it only takes a tiny bit of corner-rounding to work well.

"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!