I have on my previous 748r fitted new 14 front and a 38 rear. This gives a bit more lower gearing as the r is a bit of a bitch at low revs.
Why dont you fit a sprocket carrier to the rear whilst your at it? I would go for one that has the casting over the rear of the cush drives to stop them coming out and hitting the swing arm.
I would also go for, tart that i am, a 520 erv2 gold chain, or tsubaki similar.
So sprocket carrier, say a renthal one larger 38 tooth rear, the beauty with the carrier is you could go back down if you dont like it, and a better quality chain, perhaps even putting a couple of extra links in whilst your at it, to move your eccentric hub back to around the 5 o clock area from the nearside, hence lengthening the wheel base for more stability!