If you dont get a response just buy some gears and try things out. Thats what i did with my summit. I want to trail ride it 1/2 the year and mountains the rest. Apparently nobody else does that... Anyways tried 3 ratios before getting it dialed. Feels good to figure it out on your own. You learn more about the way your sled acts in the process.
20/46 with 74 pitch chain. its tight but fits. or any other combo that gives you 2.3:1 ratio 19:43 is 2.26 and u can use the stock chain i think so its the cheapest. IMO with the 20 on top its the more efficient. its what i run on my 163" and I'm happy