Good on you, for finding one of these!
As I recall, these were available as factory built, and as kit amps, and some of the US retailers like Lafayette Radio and Radio Shack (way, way back, when it was still a good electronics parts source) sold these in both forms.
I have a rather "rough looking" one, but it has been totally stripped, gutted, sanded, repainted, and rebuilt as the basis for a PP 6V6GT guitar amp, loosely based the Fender "Deluxe" circuitry.
It was a flea market "cheapie" which some original owner had made a valiant, but comletely unsuccessful attempt at repairing. Fortunately, the important parts (transformers) were still good. Everythinjg else inside, including the pots and tube sockets were in poor condition. Amazingly enough the tubes were in very good condition, except for the 5Y3GT, which had the locator pin broken off, and the tube (of course) was inserted incorrectly
as I received it.
/ed B