If the gas tank doesn't have any leaks then I would be really temped to not cut it up but instead put an ad on craigslist or something looking to trade someone who does have a leaky tank for the one you have, but on the other hand if your tank does have some rust inside then go ahead and cut it up.
Another thought of course is, modify the tank a bit more, make it really fit your needs, do you need the gas cap on there? sure it works for a cord end but would it work better to modify a flip open plug like the Citi-car has on the side, Home Dept sells them for RV's, with a little JB weld you should be able to blend it in and get a nice weather tight gas to electric conversion of the gas tank, something like this:
http://www.pplmotorhomes.com/parts/r...aign=partsfeed
http://www.amazon.com/Inlet-15a-125v.../dp/B000XBCUOA
http://www.amazon.com/Leviton-5239-R...=pd_rhf_shvl_1