Is there any possibility he's got the firing order wrong? It's the same as a 235, 1-5-3-6-2-4, with the distributor turning clockwise. "Changed some gauges"- - - - -which ones? Also, check to be sure the centrifugal advance hasn't locked up in the full-advance position - - - - -the Mercruiser distributor does have centrifugal advance, just no vacuum. The rotor should turn clockwise by hand, then spring back to its original position when you turn the rotor loose.
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!