If you need a new chain anyway, get a 16t cog if you don't already have it and try 16/48. You will need to get a chain with at least 120 links. You can always remove a link or two if it is too long.
Otherwise 15/44 which works with the 110 link chain.
I would use a motocross racing chain without seals (O or X-rings) because a good sealed chain needs up to 2hps for itself and I assume that's 2hp you don't have to give a way. Besides, even the very best such chain (DID 520ERT2) costs much less than a good sealed chain; as much as 1/2 as much, depending on the quality of the sealed chain.
I don't today's US market, apart from things like Megacycle and Carillo and knowing Tim Barker personally. The chain obviously presents no problem. It should be possible to get any chainwheel you need made-to-order in high grade aluminum for a reasonable price. There must be a reasonable source.
Maybe Chris Hunsicker, here in the forum, can help.
I get mine from Leonard Sieg,
THE specialist in Germany:
http://www.ls-motorradteile.de/
If you can't find what you need stateside, send Claudia a friendly email
muenning@ls-motorradteile.de
stating what you want: what bike, number of teeth, pitch. He has the data on practically all bikes. Of course, he can also supply the cog.
The chainwheels are CNC milled. I get them within a matter of days.
Sieg rides a Skorpion himself.
http://www.ls-motorradteile.de/ebene3/index.html
http://www.ls-motorradteile.de/ebene2/einige-bilder.html
If you need something very special (antique, racing wheels) he just needs either a drawing or additional data like center hole diameter, Bolt pattern and whether it has lightening holes etc.
Offset chainwheels to correct chainline front to back are also no problem when one is running a different hub.