An Indian Enfield.
I have two of them. There's a very active group of enthusiasts who can help you with advice, instructions, parts sources...
Try this site.
Or this one.
And by all means sign up for this
yahoo group. It's for Interceptor owners, but we all seem to own an Interceptor as well as other models, including quite a few Indian Enfields.
Here's a photo of mine, as it was from 1984 until this year when I tore it down to rebuild in more original form. (the fenders and engine are from a different model)