Just in case Jean does not have them, they are available at “Fair Radio Sales” in Lima Ohio.
They have a web site and show various versions of both the 6V6 and the 6F6.
6V6-GT’s are cheap — 6V6’s are not.
It seems that the fewer the number of letters at the end of the tube number, the more you pay.
Good Luck with it.
Regards; John G. VO1 CAT.