After thinking about it awhile I think I can do it with roller chain and 2 sprockets and 2 idlers. Something like this but add 1 more idler to increase chain wrap on the 2nd sprocket. I think this is on a Brandt auger



Or I could probably do a gearbox like this pretty easy as well, either way just a couple of small 1000 stub shafts and some bearings. Gearbox like this could be contained with a nice oil bath too, vs the roller chain probably exposed to snow etc.