Great discovery. I have a whole big collection of these things so heres the deal>>>
The '150' series heads were labeled all sorts of different ways depending what sort of cabinet they were fitted (or not) into. I was just at a friends place the other day and even though he has 4 150's ..they all had different markings on them. The internals are all the same FWIW though so this bit of info should settle that question.
The pic you posted of the head is the older of the two varieties the company produced. You are considering buying the big knob version but there is also a small knob version. The small knob amps have a few more watts then the big knob amps. ( maybe 10 watts more).
The cabinet pic is a little hard to discern from the angle but it looks to me like it might be a 104 - which would mean it's loaded with 6-10" alnico speakers. They sound amazing but... you'll fry them with a bass. the cab you want to go with your head is called a 106. It came with 2-15's and sounds glorious.
You should buy the whole set up and just keep looking for a 2-15 cabinet to go with the head for bass. in the mean time you'll have one of the sweetest sounding guitar cabs ever produced...and heres the proof>>>https://www.youtube.com/watch?v=UXb8ZDuICCs