So as far as i understand and thats not much the E10 is 10% ethanol.
Ethanol is hydroscopic so will absorb moisture. Probably not a good idea to leave a tank full of it for extended periods of time, could promote rust in the tank?
its also eats rubber and seals or anything thats not ethanol resilliant. This could be a problem for some hoses in the fuel system or seals diaphragm etc in a fpr or carb internals.
I have an old corvette with a small block chevy and will use e10 but i will mix it with a bit of super now n then or go pure super unleaded as still E5 over the winter when hardly used.
If in any doubt with your classic Ford stick with E5 super unleaded as much as you can.