You can go 84mm on a 61x cyl. would not recommend it from experience the sleeve is too thin. Also you have to run a different head or 760 domes instead of 701.
Bottom line: there is no advantage to increasing bored unless necessary to clean up grooves and scoring. Dont take a stock 701 at 81mm and go up to 83.5 bc it needs a bore. Unless you enjoy throwing your money away.