I looked at a couple of 216 balancers I've got around the shop, including one with a bent pulley sheave that's pretty much junk, and I believe I can drill out the rivets and adapt a 2-sheave pulley to the back side with a little tinkering. I'd probably use Allen-head bolts and red Loc Tite instead of rivets to assemble it, though.
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!