Hone the cylinders to clean up any surface rust, then use dye penetrant to check for cracks. It's usually available in a 3 spray can system- - - - - penetrant, solvent, and a powdery "developer" that makes the penetrating fluid show up when it's sprayed on. Another crack finder is called "magnaflux" where a strong magnet is applied to a cast iron or steel part and magnetic powder is applied with an atomizer spray to outline cracks. Either system should be available on Ebay.
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!