With a stroker crankshaft, and some highly modified NASCAR connecting rods, I can get close to 270 cubic inches from a 235, or around 300 from a 261. Unless you have your own machine tools, including a crankshaft grinder (I do) or know a machinist who works pro bono, it's not a very practical way to get more displacement. A bored-out 261 would be a lot simpler to build.
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!