A 270 (and possibly a 248) can be fitted with slip-in flanged sleeves and pistons for a Nissan diesel forklift engine. I'm in the process of accumulating the parts for that conversion now, as well as increasing the stroke of the 248 engine by 3/8" by offset grinding the crankshaft. Connecting rod bearings for an Allis-Chalmers tractor engine can be used in that conversion, using original GMC connecting rods sleeved down to use the smaller diameter bearings. With the longer stroke the 270 becomes a 300 cubic inch engine, and 270 blocks are a lot easier to find than 302s.

The same piston/sleeve assemblies along with a 3/8 " stroke increase can make a Chevy 261 approach 300 cubic inches. That conversion uses rod bearings for a 2.4 liter Nissan 4 cylinder engine. All the above modifications fit INSIDE the engine while maintaining the original outside appearance. That's called a "sleeper" engine on the round track racing circuit.
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!