Wow!!!!!
6xEL34......!
Is this the amp with multi colored knobs on the front panel.?
This kind of job is pretty big, and not my forte by a long shot. But I do not see why it cannot be done. I am sure you will have some set-backs along the way. Only thing that comes to my mind at the moment is filtering. Does the L120 have some pretty big plate voltages.? If so, make sure your caps are plenty robust.
Do you know anything about those Partridge trannies.? Were they a special deal for this amp, or were they a common 100 watt item for both PT and OT.
Good Luck with this my friend. Take lots of pictures.......