go for it. I dig the Beatles, and they made some great sounds with Solid State Vox kit IMO. Some of these are very rare, very hard to work on, etc. If I had the money to collect, I'd be grabbing vintage Vox tube, SS, and hybrid...
But IIRC, all the 60s solid state is messy to work on...maybe Marshall got it sorted out by '78? I could see this being for the bass, as SS was big for bass in the late 70's early 80s. I started my move from guitar to bass in the early '80s, and SS was everywhere...but I never though Marshall for bass. My first real bass amp was an old Sunn Colesium, then on to an old Ampeg SVT 8x10 then to rack gear...FWIW
make sense it could be for bass IMO, but I don't know sh*t about Marshall for bass