At the RPM the average 235 usually runs, one overweight lifter shouldn't present a problem. If I was bulding a tight-winding small block Chevy V8 like a 302, I'd be upset about a lifter a couple of grams heavier than the rest, but that engine would go to 8K RPM on a routine basis. If a stovebolt engine sees 4K even occasionally, I'd be surprised. Small bore/long stroke engines build lots of torque, so high RPM that would result in valve float from a heavy lifter just isn't necessary.
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!