The years of looking at fuel problems have fogged the brain (I was too polite to say sniffing the rag was the cause – it is not a fuel problem but an engine problem.
Look what happened with cars – the governments in their wisdom said they would stop selling leaded fuel.
The world did not end – manufacturers quickly made engines compatible with unleaded fuel, of all sizes and all power outputs.
Most found that, actually, in spite of all the fuss, doom and gloom and supposed threats to liberty – doing so was easy. Many used the opportunity to redesign engine plants at the same time and remove the weakest link (humans) from the engine assembly lines. I have one car 16 years old and another 14 years old. Neither has ever had an engine problem. My Dad finds that incredible.
Simply stop selling engines which use leaded fuel, and the problem will go away.
Old cubs and the rest with 60 year motors can still fill up with fuel and a dose of lead from the bottle, just as old cars can, if you really want the charm of the old fashioned experience.