unleaded gas won't be an issue, especially with that little mileage
I'd suspect the pertronix first off, seems to me everything points to that - "have spark" doesn't mean you have enough spark or at the right times, like under acceleration or load - gas doesn't sound like an issue, but there couldn't be any harm doing the carb, years take their toll on gaskets and rubber bits, more so with ethanol if that's a CA thing, float bowl might not be filling
you're likely not getting responses cuz us other 283 runners haven't had anything like that happen, mine tends to stumble and complain until it gets well warmed up then goes like a goosed rabbit
but I have a stock [points] dist, never have to use the choke except in the dead of winter
Bill
