I would recommend either of the following speakers for a 'Twin like' 80+ watts amplifiers. I would say first though, that if you are going to be merciless and push that amp hard n' loud for an hour or more several nights a week, you would do best to buy a JBL, or Electro Voice, maybe Fane (I know only that Fane is British and can take long-play punching and dare you to play louder). I'm just commenting from the 'old school' type speakers. You know, big ceramic magnets and cone paper tougher than rawhide. Here are my picks for the Derby: All these speakers can be bought in the 60-85 dollar price range.
The great sounding Jensen Blue label 12" found in Fender amps. A stout bit of history and as fine a guitar speaker that I know of. I am not sure of the dates of mfg. but my best guess would be late '70s to the early 90's time span. see pic. I guess this period of time for speakers could be likened to the Muscle Car era in American history. All the big names in amplifier manufacturing were competing for the ultimate power and decibel level award. So, IMO, this is the era you want to try and buy your tried and tested high power tube amp speakers.
Celestion White label G75-12 a crisp sounding speaker that loves Humbucker pickups and any type of effects pedal nonsense. Basically produced en mass in England around the same time as the Jensen. They took production out of England and you want the ones made in Ipswhich England. I am almost sure that celestion still produces this speaker but like I said, no longer made in Britain.
You might also want to look at the Vox (Wharfedale of England) also. The Wharfedale Speaker Co. is the British made speaker that is as well crafted, sturdy and good sounding as the JBL and EV speakers but they built many more home stereo speakers than guitar speakers. A couple yrs. back their 12" guitar speaker labeled "Vos" and standard issue for the AC-15 and AC-30. These speakers were constantly up for sale because the AC-15 and 30 Vox amps, no longer produced in England, were and still are all equipped with Wharfedale speakers labeled "Vox". A lot of the people buying the tube line of Vox amps thought they had to immediately swap out the speakers to get that real 'AC-30' sound. I don't think most of these Vox buyers even reached the break in stag for these speakers.
OK; those are the speakers I would look at for a great sounding 'Twin' and staying within a budget of at or below 200 dollars for the pair.