Guitarboy2828, I shall proceed with a more-or-less standard build. With space for later expansions. The Mojotone cuircuit you show has stuff on it not included with this kit, or shown on the (Weber) diagram supplied earlier by Karel. But all of it is discussed in detail on the internet, anyway. Pro this, Con that.
You mention a 5W / 1W selector switch, but I am at a loss of how to accomplish this without a mess. Your ideas on how to do this easily? Internet seems to imply a dropping resistor after the diode, before the first big cap, but this apparently deadens "tone". Karel says I can play with the screen grid voltage by altering the screen grid resistor, I ordered a 22K fat pot for this purpose as well. But, other sources naysay this idea due to the increased voltage difference between the grid and the HT side... Not that I have the faintest idea about how these things are supposed to work. I only know that valve amps work well in Hi-Fi, and with guitars they tend to amplify stuff never heard on cheap transistor amps, thereby messing up years of perfecting (hidden) bad technique.
My initial mods will include a new faceplate with space and holes for future expansions (like a bright switch, tone pots x 2, decent On/Off toggle, maybe a Standby toggle (not required due to diode valve rectification.. ? Bah. Cannot hurt.)
Mods to the circuit will be the Screen grid pot, added to the 10K resistor. It seems that any mods to this circuit usually results in less "tone". And then some swear they improved matters by re-designing extensively. Maybe we are spoilt with too many knobs on our more modern amps. ( I think less is more. That may be why I enjoy the Ibanez TSA15H. Which insists on rejecting my "new" Strat-alike. Too much Strat brightness and sharp, twangy tone. )
Mods to the existing chassis will be lots of ventilation holes, and shifting the output transformer to the side on an angle plate, to allow space to fit the valves on "top", implying the chassis will not hang vertically as per Champ, but sit "flat" as per normal amp head, with the friendly glow of tubes on top of the chassis, faceplate front. Improving heat dissipation too. This will be the least invasive process and leave the chassis almost standard if I ever feel like going the traditional route. The chassis will also receive two bolt-on aluminium angles on the sides for mounting in the proposed head cabinet, with the standard mounting holes in the existing faceplate used for stand-off pillars to attach the new, improved faceplate. Which leaves extra space for me to try and solder all the wires. Thus no
messing up the rather shiny, neat standard face.
Speaker? 10 Inch speaker lying in box, waiting for wood.
This is going to be fun. I hope.