A 4 1/8" bore size in an engine block that began life as 3 3/4" in the 1955 265 engine is just pushing the envelope a little too far. AMC did the same thing in the early 1970's with displacements from 290 to 401 in the same block. MOPAR went from 273 to 360 in the same block with similar results. Ford- - - -221 to 351. I turned a 426 hemi into a 547 cubic inch truck pull engine by filling the cooling passages with epoxy, boring all the way through the cylinder walls in places, and installing flanged sleeves. It lasted for 2 1/2 pulls before breaking the crankshaft into 3 pieces. Putting big cubic inches in little engine blocks doesn't make good nonsense, no matter who is doing it.
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!