I know there's a couple guys on the SOHC board who built really good 836 motors that are surprising. One guy has an 836 with a good cam, ported head, aftermarket rods, and a lightened crank that pulls the front wheel up in like 3 or 4 gears. Pretty surprising. A nicely done 836 would be a world of difference from a tired 750. Probably cost you about $1200 to do a decent budget 836. That's using Ken's $250 pistons and $250 cylinder boring, a mild aftermarket cam, new springs, and a quick home port cleanup.