Fender Twin I believe is 6L6 power tubes & The pin pattern is different than EL-34/EL-84...but 7027 is same pin pattern, they are softer than 6L6, will break up earlier than 6L6. You will probably have to have amp rebiased to run different power tubes.
Been a minute since I had my head in deep, I'm running digital & solid state gear now. I believe Mesa sources Sovtek tubes & have a very hi rep for matched sets.
I would choose Sovtek over Groove Tube(Chinese).
Another Russian tube mfg'r is JJ.
Links for Mesa & JJ
https://store.mesaboogie.com/categories/shop/tubes.html
https://www.jj-electronic.com/en/vacum-tubes?start=24
I don't know why links fucked up, but just Google Mesaboogie vacuum tubes & JJ vacuum tubes.