I'm not sure I get the question. Are you asking what preamp
tubes I would suggest? That's a personal preference issue, but I have no problem with those old long plate GE's if that's what you are referring to as "old GE 12ax7's". If you have a bunch of cash around Bugle Boys are probably the most
musical of the ECC83/12AX7 types, but that's
my opinion, and truthfully those Holland tubes are stupid expensive (also IMO).
There are lots of good preamp tubes out there, even some of the newer stuff is pretty darn good, although IMO older European and American made tubes are unquestionably superior. A lot of them aren't real pricey either. If you get used tubes (preamp tubes generally have a very long lifespan, some can be measured in
decades) you can sell them for around as much as you paid. You should just experiment and see what
YOU like and sell the ones you don't.
Also, I am not very familiar with Model T's. I haven't played through one since they were new in the 70's.
I'm more of a Sundholm era kinda Sunn geek; as I think I've posted before, in my mind the Sundholm era Sunn's have the same type of "mojo" as the Leo era Fender stuff. I have some later Sunn gear, but the old stuff is what I'm truly passionate about.