261 blocks are scarce and E$$$$PENSIVE. A 235 can become a 256 cubic inch with the right bore/stroke combination, using big block Chevy V8 connecting rods and pistons for a Japanese Diesel engine, or a Ford 223 six piston. That setup uses a 4 1/8" stroke, and makes more torque than a regular 261 due to the longer stroke. Increasing the stroke to 4 1/4" gives 263 cubic inches with the same piston and a different length connecting rod.
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!