There are places that sell gasoline with no alcohol, but unless you are willing to only take the coach one half tank away (so you can use the other half to get back) you will have to rebuild the fuel system. You can look at Ethanol-free gas stations in the U.S. and Canada
and see if any are nearby.
It does sound like you need the Thermoquad rebuilt first. And, if the oil is relatively new, you can run with it and the gasoline will evaporate out. You can't do that again.
Except for the carburetor that you are having rebuilt, none of the non-steel parts of your fuel system are E-10 compatible. That can be changed, but it will be work.
You should also start finding new lube oil. The current stock for passcar is not good for your engine. Your 440 need more ZDDP than is allowed in emission controlled engines. Get into the classic and hotrod sites and read about it. I had (have) the same problem (s) with my antique coach.