Hey Dennis,
You didn't say gas or diesel. A popular option with diesels is repowering with a Cummins, like the ones they put in pick up trucks. There are kits made to do this, just need to look around some to find them. Southern Indiana? Have you talked to Otis, at Wright Bros. in Borden? He may have a 1650 engine. Another source is in Greenville, IL, Ollie Schaefer might lay his hands on an engine, Phone 618-664-3050. There are probably more sources, and options, this does give a place to start.
Take care!!
Andy