You might want to do a lot more research before jumping into vintage British motorcycles. You do know that they use Whitworth tools, not metric, not SAE. So, you'll need those. Ever heard of Lucas electrics? They tend to work sometimes, not work sometimes, usually when you need them most, they decide you really don't. Old bikes in general leak, Harleys and Brit bikes aren't known for cleanliness, they leak and can be difficult to fix. Old Japanese bikes are a lot better at oil control and much cleaner. After all these years parts are going to be expensive, especially since Triumph/BSA/Norton all went out of business. Triumph has been reborn and now produces some really good scoots.
If you really want to spend you time trying to find parts for and fix a vintage Trumpet, then all the power to you. If you'd rather ride and do some tinkering, modifying, I'd recommend getting a new, or new used Triumph, (this century). Gonna be more reliable, easier to get, easier to maintain, better riding, better handling bikes compared to anything from the 60's. They have new Bonnies, Thruxtons, etc. You might want to consider this route. Either way, be careful when riding in the street, everyone is trying to kill you.