uh... usually performance<>gas mileage
if you are comfortable rebuilding the carbs then in my opinion a pro rebuild isn't going to get you anything you can't do yourself except for some very shiny-looking carbs that make you feel good about all the money you spent /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif
I'm not sure if your carbs have the throttle-shaft wear problems that SU's have. Re-bushing the shafts(if applicable) is really the only thing a pro would do that you need special equipment for (and you could just get them re-bushed without them doing the rebuild for you)...
Unless you're dealing with some wicked vacuum leaks or constant fuel leaks you are not going to get much improvement over stock from a rebuild.
I'm also of the opinion that electronic ignition is not the magic performance pill everyone is looking for.
A better flowing exhaust would be a fairly inexpensive upgrade that will give you a little improvement.
After that you're into the territory of better cams, porting the head, etc etc etc.
Pick up Kas Kastner's book on triumph tuning and read it a couple of times to get an idea of all the crazyness you can get into if you're willing to spend the dough.
www.kaskastner.com
And think about this stuff long and hard. What are your goals? Do you want better straight-line performance? You want a higher top speed? Better handling? Are you going to persue a national SCCA championship? Autocross?
or do you just want to have fun driving windy twisty roads?
Set some parameters and goals and then think about it again. It can be an endless spiral.
In my case my goals are simply to have fun driving. I've done nothing but tune it up to stock and it runs very well now. 30 minutes on hilly country roads and I'm satisfied. I have a smile on my face and I'm good for at least another week of my daily commuter-coma drudgery.
Actually the best improvement I did was rebuild the suspension. It was sketchy at best before and after the rebuild it was like a completely different car.
Join a club if you can and go on some runs. Get in good with them and ride along in other member's cars. See what you like about them compared to yours. You could very easily turn this into a frustrating experience of spending money on things in search of some elusive goal. I hate to see this happen to our dwindling supply of nut-jobs who love these cars. /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif