Put an ad in the "parts wanted" section of the forum. If someone has a 235 block they're about to scrap out, the main bearing bolts are the same as the 261. I believe main bearing bolts for a 216 will work, also. Occasionally, I see main bearing caps and/or bolts on Ebay, so check there, also.
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!