Hi George,
Speakers, well, if you want to go for the classic 60's Vox tone then get a couple of celestion "blues", if you want the 70's rock get the celestion greenbacks or if you want another great sounding speaker try the celestion vintage 30 (that's what I'm sticking in my cabinet for now!). You can download some samples of these speakers from the celestion web site (
www.celestion.com). Getting hold of them shouldn't be a problem as they are the dogs dangly bits when it comes to guitar speakers!
I'm trying to be quite faithful to the original so am not going to be changing the circuit too much, the idea of a master volume is a good one, though if you want tube distortion just crank it up loud and enjoy it - forget the neighbours!
Let me know how your build goes,
Mark