We've been running the "corn gas" here since way back. There are stations (and you can find them by checking websites) which sell Non-oxygenated fuel. I know where my local stations are and that's what I run in my cars most of the time. The exception being if I am out driving around and need gas and have to run the ethanol. The difference I notice is my temp gauge goes up a bit more when running ethanol and I have to keep the timing at TDC to stop the pinging but I've never replaced a diaphragm or a seal of any kind in the last 15 years. On the J there really are only three - the diaphragm in the carb which the modern replacements are made to work with ethanol, the two in the fuel pump, which can handle it, and the neoprene fuel line hose which goes from the fuel line to the fuel pump which always dries up and rots regardless of whether or not you're running ethanol. I've put 20,000 miles on one of my cars since 1997 and 10,000 on the other since 2001 and never had a problem but I do run non-oxygenated fuel most of the time.
The Henry J shop manual states the timing should be set at TDC but there was a KF service bulletin (don't have the number right off hand) which says the power and acceleration can be increased if the timing is advanced 3 - 5 degrees. If I do that, the engine pings so badly it can't be driven. Other than that, no problems.