[Arran]

Metal tubes will not fit in this set, they were intended to use G or ST style tubes so the shield bases are made to fit the narrower bases of those types, the hole in the shield bases is just narrow enough that it won't accomodate a metal tube. They are all available but some are more money then others if you want NOS types. If the tubes currently test good it's doubtful that you will use the radio enough to wear them out. This only applies to three of the tubes, the 6K7, 6Q7, and the 6A8, the 5Y4/80 and the 6F6 do not have this problem.
Regards
Arran