I tested several speaker combinations and agree with Andy and DH, the 8 & 10 combination is outstanding. A 12 cuts through in a band situation but so does the 8/10 combination. I also tested ceramic and Alnico speakers. My favorite is the ceramics (the Jensens listed in the book) with the Two Stroke and a Tele. Recently, I’ve started using the new Jensen Jet Falcon 10, it’s great. I received the 12″ version today and will test it soon.
The cathode bias design does a lot more than just allow for self biasing.
The single-ended, cathode biased circuit (although not as efficient as a
push/pull design like your 5F2a amp) has a singing, compressed tone feel that is fantastic.