I'll relay the info about leaving the paint alone. It actually belongs to my father; I just helped lift it into and out of the truck....and get it running.
The hopper cover isn't actually original; the previous owner found it in a recycling yard. I guess it's correct for the engine, though. I think some of these IHs would run on kerosene too, so I'm not that surprised it ran on varnished gas. This is the first antique engine he's owned and I have none, so it's fun.
Not bad for a freebie, eh? Well, free at the expense of a favor down the road...