Well established fact is Sea Ray is known for factory installed trim tabs are very undersized. Call Bennett and ask them to recommend replacements that will keep the bow down.
Start the good port engine and press the parallel start switch while you attempt to start the starboard engine. Get the batteries load tested or just replace them. Cheap insurance.
Keep the carbs and have them rebuilt/tuned and add electric chokes. Install HEI ignition distributors. I have run Qjet carbs with DUI (Davis Unified Ignition) distributors for 9 years with no issues.
I suspect it's an add on but potentially dangerous one. If the 2 outside receptacles are connected to shore power check to see if the cockpit receptacle is live. If it is someone could get electrocuted by the exposed terminals. Doesn't matter if there is a hinged cover on them.
Of course timing could be an issue but start by checking the condition of the distributor cap and rotor. If moisture is present it will cause ignition cross over and cause those symptoms.
One way for you to determine if the engine is reverse rotation is to check the location of the plug wires on top of the distributor. Compare to the port engine. My guess is by 1992 both engines are standard rotation and one has a reverse rotation outdrive.
At my yacht club the majority of generator problems are with Kohlers. With all makes the most problems are with newer boats that have computer controlled integrated generators that tie into the carbon manoxide detectors. The older simpler generators seem to have very few problems.