Rob already asnwered your question ... I'll post anyway - had already typed it out!
Can't tell from your figures what you've got, Ted. I'm assuming you have a 530 (5/8x3/8). I've never seen a 630 on a twin. Even owners of later triples that had 630 chains have dumped them - total overkill in this day and age of high quality lightweight chains.
I'm running a 520 DID VX3 on my twin (which has a whole lot more power and torque than a stock twin). You can buy gearbox sprockets in 520 ready to fit (not sure who the suppliers are). I had a 530 in my parts bin and I sliced a sliver off it to get a 520 width using an angle grinder and cutoff wheel mounted in the cross slide of my lathe. Rear sprockets should also be available in 520. If you couldn't be bothered with sourcing 520, just fit a decent 530. I bought a blank in alu and drilled and machined it to fit my non-std (Triumph Legend 900) hub, but I'm sure you can source 520s and 530s to fit straight onto a stock hub.