Be aware that when an alternator goes on load as demand increases , that 'drag' on the engine increases due to the way the alternator works in that it does sap power to some degree
If intent on running dynamo - add a 15-0-15 ammeter to check load at anytime since 22 amps is not much and you can see which way the wind blows. Always used one on various old heaps back in the day for reassurance ..
Got my fingers burned by local tester in the 1070s by using it beneath my 1966 midget .. it was one of the many issues upon which it failed , although it was particularly singled out as downright dangerous and utterly prohibited . I suppose that it could be possible if the pipe was positioned such that it was totally protected which may be what Triumph did ,as the tester stipulated that abrasion and possible cut damage was the reason.
Nope . take off the water pump .. allowing for the possibility of the long pipe being knackered and twist/lever the plug out . It looks bad and could give at any time . As a bonus - removing the pump will allow examination of its condition and some access to the water jacket to clear local rubbish away to give some reassurance .
No Must be metal .. had my wrist slapped by the MOT man years ago as the fear is unseen abrasion of the pipe - Flex pipe obviously allowed at each end .