Will try and draw up a diagram of what i mean, but basically like you say about removing the lamp holders first, the underside of the tailpiece is all open so i will have access to the tail lamps, and when installed these will squash the lenses inbetween the lampholders and the fibreglass , so if the lenses do break its a 30 second job to change them
also, i took the carbs off to have a closer look... google didnt prove to be much help so with a lot of guess work i eventually found that the floats were dropping too low, which in turn caused the needles to drop too low and jam against the adjustable plate attached to the floats, i also noticed that the floats were catching on the side of the bowls when i removed them, after a closer look i found that the floats are contoured to fit the float bowl.... and they appeared to be in upside down. could this be why the bike was left to rot in a barn for so many years?.
anyway, i turned the floats around, set the height (again, mostly guesswork but just below the overflow), tested them and they no longer leak!, i even got the engine to fire on the #2 cylinder! (should probably check for spark on the #1 as it didnt seem to be doing much), very happy with how things are going right now