Do flex fuel and standard vehicles have different lines and seals or is that just an assumption?
I can tell you that they have sensors that are able to detect the amount of Ethanol in the fuel as it comes into the engine. Thats why you can fill up one tank with E10 and fill up the next tank with E85, or any combination in between. This is the main difference between flex fuel and non flex fuel vehicles.
I also have a Honda build going on in addition to my ranger, it is quite common to do an E85 tuned turbo build in a car from early-mid 90's while using lines,components that came on said vehicle from the factory.
All I am saying is, that LOTS of people in the Honda world, and im sure in the Ford v8 world do E85 builds with no adverse affects. If you store your fuel properly, keep tanks full, and use some Ethanol stabilizer the advantages FAR outweigh the small negatives.