Yes it would take a lot of time to both figure out the correct parts & find them, hence why I suggest looking for an engine block (the sort that RC modellers have removed/lost bits from) and transferring the good parts from your engine to that one. As I did to restore the yellow Tiny Tiger which must have suffered a similar failure.
And refilling the tank every hour.
Don't forget they advertised them as being suitable for powering all sorts of equipment, plus battery charging (just imagine your miles from anywhere with a flat battery & the O&R won't start either), or even cook the worlds smallest goose (below).
David