The first thing to consider will be installing some type of 2-sheave crankshaft damper to be able to run an extra belt. Drop me a PM for some suggestions on how to do that without finding one of the 235/261 2-groove dampers that are as scarce as honest politicians! If you're doing a complete rebuild on the 261, think about making a road trip to middle Tennessee to get the block machined for a full circle rear oil seal. If the 216 will be looking for a new home eventually, I'm interested.
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!