Sorry but i cannot help you with info on your bike although i'm loving that shifter on the stem. Most unusual. Maybe other can help, Looks quite nice though.
This is what the late great Sheldon Brown had to say about stem shifters -
A type of shift lever which mounts on the shaft of the handlebar stem. These were popular in the late '70's and early '80's because they permitted shifting without having to lean down to reach down-tube mounted shift levers. Stem shifters, along with brake extension levers, encouraged riding using only the top of drop handlebars. This riding style was popular at the time, because many casual cyclists bought bicycles with drop bars for reasons of fashion and style, even though drop bars were not suited to their low-intensity riding style.
Unfortunately, this riding position gives rather poor control of the bike, mainly because the hands are too close together for good steering control.
Stem shifters also present a danger in a collision. Depending on what gear you have selected, stem shifters can be like having a dull knife aimed at your groin!
If your bike has stem shifters, consider upgrading to something safer and more convenient. '
Taken from his site so if there's any copyright issue please delete but I thought it worth adding here given his concerns!
Today is the yesterday of tomorrow.