If i was doing a long storage generator I would buy some of the canned gas and have stabile for all the fuel I had at home or purchased as the event came on.
The older alternators like the big subarc's I used to run and work on needed an exciter. For the alternator it was just a momentary 12 volt zap.
Had an interesting one on my old massey ferguson: it was converted to 12 volt at some point, and had a GM alternator. It wouldn't charge until I revved the rpm up to 2000ish. At that speed, it would self-excite and be fine. Before that, no charging. Not ideal.
Simple alternator with a built in regulator, it had a big battery output post terminal, and two spade connectors. One was to sense battery voltage, and could be tied directly in to the output lug. The other was for the charge indicator lamp.
I looked and looked, and finally found documentation on the internals of the alternator. As it turns out, it uses the small amount of current passing through the charge indicator lamp as startup excitation current! I replaced the missing bulb in the charge indicator lamp holder, and it started working right from low rpm startup. I couldn't decide if I thought it was ingenious or really stupid.