265's were notorious for piston failures. The skirt would crack away from the invar strut that limited expansion from heat, and produce a knock at idle and part throttle. Unless you're doing a period-correct restoration or have some other reason to retain an "original" engine, a later model, larger engine such as a 283 or a 305 would probably be a better choice. Virtually all the small block V8's from the late 50's through the early 90's would be a bolt-in swap with the 265.
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!