I have a Blues Junior in that Brown Tolex with a Wheat front. I like it because it isn't your every day black tolex BJ. It was a special edition with a Jensen speaker. I really like the look of that concert.
Interesting that it has a tremelo and no reverb. A little delay would be cool with that amp.
I once owned one of the early blackface Super reverbs, It has a 4/10, and was a wonderful amp. Not easy to move around but amazing tone.
I sold it in the about 1970, but wish I still had it of course.
I think that concert is a great score. I have heard that they go for around 800+ in good shape, so it depends on how much the guy owed you if it was a good deal.