Hi,
I'm just a bass player. I did hear the Model T with a Les Paul, it was not too Hifi, got a good bottom. There has been a long discussion KT88/6550 on this page. You can use the KT 88 and the 6550 as they are (nearly) the same tubes. You can check out a tube-datalist, there are plenty of them in the www.
By the way: I live just across the alps...it was no problem to get the SUNN amps here. The big one (Sunn 2000S, 1000S etc) are quite expensive with their weight (> 20kg no DHL or UPS.. just Fedex). I think the small amps are very interesting as they do have "just" 60W RMS but you can crank them even on a small stage without beeing too loud!
If you want to get some info abot P&P to Europe please feel free to contact me.
Greetings
Oliver