The extensions bring back very bad memories, an early bike I had had screw on slugs to extend the tubes most god awful things devised by man mine came loose at speed on the freeway. There is only one way out of a high speed wobble and thats to lift the front wheel not an easy feat on early iron. Then I had one tube come right out of the triple tree landing was very bad, messed up for months. Should have been tightened and then welded properly and then re machined. A good plan would be to check them weekly like and if found loose at all PREY and redo. It is a very well done build you could help me anytime.
PS I still prefer my 33 year old BMW R-65 (red headed step child of BMW's) to the car any day. Riding since 1965 one loss of time incident 3+months still feel it today.