Hello,
Since RotLE came up, I thought I'd join in. To solve your pipe problems, just get in touch with RotLE member Walt Metzler in High Springs. Walt will take your head off (nothing personal) and remove the threads for the exhaust pipes.
Then he will machine a spigot for each, .002" less than the new holes. After the head is heated and the spigots placed in a freezer, they are mated. After that, they will never get loose. You have the added advantage of using any of the pipes available for the pre-oif bikes, a very wide range indeed. If you want top end performance, use 1.75" headers, for more mid-range, try 1.5'. The stock 1.25 are too small for efficient flow.
Walt can also flow your head and install larger carbs, either Amal or Mikuni. After 2 years of screwing with new Amals, I am in the process of switching to Mikuni on my '79 T140, which is very similar to yours. I expect to get nearly 60 HP on the dyno after that. Maybe even a few more.
If you are a RotLE member, you will get a discount on this work, and also from some 40 other dealers and parts folks, such as Don's Triumph Garage, Baxter Cycle, Palm Beach Triumph, Flamingo Cycle and many more. We also sell direct for Skykingproducts.com, Vanson Leathers, European Spares and others, all at big member discounts.
While RotLE is in the information biz, we don't have a forum, yet. We encourage owners to ride their bikes and provide venues for them to do that. July, 2005, we rode from Canada to Key West. July, 2006, we will have a rallye along the Blue Ridge Parkway. May, 2007, we are touring Ireland. Come along.
You can contact Walt at 386 454 4353, but not today. He is in Maine, doing a job for FPL.