Sorry, the pedant in me must correct your use of the name of this town just to the west of Edinburgh. The full name is Borrowstounness, but it is always contracted to Bo'ness, not Bow ness.
I have attended the Bo'ness Revival Hill Climb every year since it was restarted about 8 years ago, and the event has gone from strength to strength. The hill is not very long, and the faster cars are posting times around 35 seconds, but it is still good spectator sport with around 100 cars competing in 2016. They put up a small grandstand at the courtyard where the racers have to zig-zag round two houses and where mistakes can be made. There is full access to the paddock, although it does involve a walk through the woods. If you can wait for a break in the racing, a free bus runs up and down the hill.
There has always been a display of classic cars at the event and I have been there with the Caledonian Centre of the MGCC mostly. This past event was bigger than ever with a new much larger area for the classics, plus a display ring where interesting cars could parade and the drivers be interviewed.
I'm sure the organisers would be delighted to welcome Triumph clubs. Many other clubs are already present.
http://www.bonesshillclimb.org.uk/