Hmmmmm- - - - -looks like a HEI distributor from a Chevette will work, with a little surgery to the drive end. There's also an electronic trigger conversion for a Mercruiser Marine 4 cylinder that might be adaptable to the distributor that's on the machine now.
www.ebay.com/itm/376813174793Welllll- - - - - -it's got a Delco distributor, and it's already been converted to the same electronic trigger I posted. Got a new one on the way, just in case the one that's there already might not work!
Jerry