Drop the oil pan and inspect/adjust the rod bearing clearance before you crank the RPM up. Babbit rods aren't any more prone to failure than insert bearing engines, but excessive rod bearing clearance on either one will hammer the bearings out of round and result in rod knocking, low oil pressure, and crankshaft damage. It's possible to install insert-converted connecting rods, and 216 engines have enough piston skirt clearance to change rods from the bottom without removing the cylinder head- - - -235's don't. Be sure the crankshaft journals are round and smooth, and measure them to see if the crankshaft has been reground undersize, then install the proper size reconditioned rods or insert bearings.
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!