If there's enough wear and/or carbon at the top of the cylinders to hang a fingernail, don't try to drive the pistons out past it. The rings will hang up, and probably break the ring lands of at least a few of the pistons. Instant paperweight if that happens. Reamer tools for cutting that ridge away are inexpensive, or some parts stores will rent you one with a deposit. Also, be very careful not to nick the crankshaft bearing journals with the threads on the rod bolts- - - - -stovebolt cranks are tough- - - - -but not hard, and it doesn't take much effort to put nicks in the bearing journals. Use some short pieces of 3/8 inch rubber fuel hose over the bolts to cushion the threads when removing or installing rods and pistons.
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!