I don't know Lifco, maybe someone else does.
Are the mystery tubes octal based? (8 pins with the fat post in the center)
If so, my first thought would be 6L6s. SO look at the wiring. You have the two tubes - does the socket wiring look similar on both, or is one wired completely different from the other.
If there is a pair of power tubes, is there a wire from pin 3 of each running into the output transformer? Or some other pin. Is pin 8 grounded? How about pin 1? Are pins 1 and 8 wired together or is there something different going on at pin 1? If pin 8 is not grounded, then does it have something like 200-500 ohms to ground? That resistance would mean cathode bias, while grounded pin 8 means fixed bias... most likely.
If pin 8 is grounded, then with the tubes removed, is there some negative voltage on each pin 5?
Look at pin 4 of each. Is there a simple wire connecting pin 4 to the other pin 4? Or is there a resistor to each pin 4? A resistor of probably 1000 ohms or less.
Is there anything wired to pin 6?
I asked if the two large tubes were wired similar, thinking there was a pair of output tubes. But it is also possible there is a single output tube and a rectifier tube. The output tube would have wires running to the output transformer, but a rectifier tube would have four wires running directly to the power transformer. That would be a pair of probably red wires to pins 4 and 6, and a pair of probably yellow wires to pins 2 and 8.
Chances are the circuits in this amp are just like the circuits in most other amps. Large tubes are usually 6L6, especially on older amps, but the smaller 6V6 would not be uncommon. EL34 would be a lot less common in my view, but not unheard of. Outside of AMpeg, we see darn few 7027, and there are other various octal power tubes. if it is not wired for the basic 6L6 or 6V6, then the wiring would likely suggest what tubes it wants to see.