To be absolutely sure, pull the cylinder head. A 261 has a 3 3/4" bore. A 235 is 3 9/16" They both have the same stroke but the 261 crankshaft is forged, not cast. 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!