This "O-rings vs modern fuel" subject has me bugged.

OF COURSE there is O-ring material that stands up to modern fuels. There has to be, O-rings are used everywhere in commercial fuel delivery systems.

The problem is that they aren't ready made for your application. The solution is to make your own out of the correct material. For example, you should be able to buy everything you need for one engine from the O-ring Store for less than $20. I picked Viton cord and their special rubber-toughened glue. Now you need the diameter.

Or, send them in some samples and get a quote on having them made for you. You could go into business!

R.