Tach is somewhat easy, but gear indicator is something I am unfamiliar with.
Pretty much any tach that will work with a single cylinder engine. Make sure it says that its compatible from 1-12 cylinders (thats how they usually label it). I found that the Equus are the easiest to find, and look decent.
http://www.iequus.com/Product/Gauges/
I believe models 6068, 7068, 8068, and 8080 will work.
Without an aftermarket ignition you will have to install it via the spark plug wire. You will also have to find a mounting point.
Here is what the black 6068 looks on my bike: