Welcome to the world of Datsun Roadsters! Check out 311s.org as it seems to be a more frequented forum. They have a vendor links page with a long list of parts sellers/suppliers/etc.
If you have the stock SU carbs, you can find rebuild kits on ebay, or from vendors like Datsunparts.com and datsun-roadster-parts.com. There is also a company that does complete re-furbishing of the carbs, you can find them on that vendor page on 311s.
You can also find gauges and gauge sets on ebay. There is a seller McBoulevard that usually has a large stock of parts. He is 311s.org member MCB. Some people also send their gauges out to a member, I believe his name is Jon Frampton (but could be very wrong on that name) who meticulously restores the stock gauges. I am in the process of re-doing my interior and have chosen to go with all new gauges from Speedhut.com You can customize gauges on their site as you can on autometer.com
Congrats and good luck!