What was the outcome??

I am currently going through the exact same senerio on both of my 502's. Was there ever a final solution?

Symptoms of Ignition module to a tee going bad

Can you describe the "backfire" or "mis" or "stutter" or loss of wot feeling like the carb isn't getting enough fuel...one of my motors exitibited this behavior (a slight stutter at WOT) and it was a lifter.

When a motor is running like crap especially with bad fuel You NEVER try to run it out. You can destroy your engine doing this. It didn't want to go over 4200 RPM for a reason. You may have burnt valves now. Pull the carb apart if you know how to clean a carb. If you don't then take it to someone that does. Don't mess with a carb if you don't know what you are doing. sounds to me like you initially had a case of bad fuel. ( I NEVER run old fuel in my boat - I pump ALL of the gas out in the fall ) AND you made it worse by trying to run it through the engine. When it started to sputter you should have put it back on the trailer.
Steve

We ran from a bucket and both carbs are brand new

Was there an outcome to this issue? I have this going on in my 350mag, to start with it would not start at all, changed ignition sensor in distributor , cap rotor coil and it runs good up to 4grand rpm. ?thanks