A major change to the dimensions of the 216 was made in 1948- - - -different connecting rod big end width, and different outside diameter of the main bearing shells, but only by about .004". All the 216 and early 235 engines ran Babbit metal lined connecting rods. Replaceable rod bearings didn't come along until 1954 with the 2nd, generation 235 engines.

I replace solid forged 216 crankshafts with drilled and pressure lubricated 235 shafts and replaceable bearing connecting rods, and use different compression height pistons from a Buick 215 V8 to compensate for the increase in stroke. No, it's not a drop-in fit- - - -some machining on the crankshaft is required. That makes the "216" a 224 cubic inch engine- - - -more if the 3 1/2" cylinders are bored oversize.
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!