Finding exactly the same rev counter may be difficult as it's unlikely to still be in production. You could use a Defi rev counter though. Defi make excellent gauges and it's parent company is Nippon Seiki (Which is owned by Honda). Some used ones are sometimes available:
http://page9.auctions.yahoo.co.jp/jp/auction/k139823058
This one would need a controller which is just a small box.
& another (White face) inclusive of the controller:
http://page16.auctions.yahoo.co.jp/jp/auction/u36855946
1st one's smaller (80mm diameter) than the 2nd which is 120mm diameter.
This one has a shift light which could be incorporated into your dashboard:
http://page16.auctions.yahoo.co.jp/jp/auction/u36907605
They're all discontinued models, but parts are available used - in Japan.
These are mostly used for cars, but can easily be used on a bike too.
Can be sent for 2 cylinders, no problem.
Also has an adjustable warning light (which can be used as a shift indicator).
Probably better than the original you're after and looks kinda similar too.
HTH