Glad I could help. I did a face plant on the desk shortly afterward.
To answer your questions about power supply voltages:
The voltage supplied to the center tap of the output transformer is specified as 475Vdc on the 40W amplifier and as 440Vdc (Sams shows 420Vdc) on the 30W amplifier. The power transformers are different between the two -- the 40W amplifier does away with the filament winding and uses a pair of 1N2863 silicon diodes in a voltage doubler configuration to get the higher voltage.
The input amplifier and phase splitter use the same voltages in both amplifiers -- so the dropping resistor from B+ to B+2 has been increased from 39K to 56K.
I don't have enough information to judge the relative efficiency of the 5U4 used in the 30W amplifier versus the pair of 1N2863 silicone diodes used in the 40W amplifier - given the difference in configuration.
I also don't have enough direct experience to appreciate the relative longevity of the tubes when supplied with full B+ before their filaments are fully heated. I've done enough reading on the subject to make the decision to add the circuitry necessary for a delayed or soft start B+. The cryptic service notes I have from 1968 do show replacement of output tubes due to running hot. The 12AU7 phase splitters were replaced at the same time though. Again, not enough information.
I have all of the same models in the photos you supplied and am gradually working my way through them.
I will let you know if I see another 403 faceplate. In one of my earlier postings I show the difference between the 402 and 403 faceplates. Most of the 403's are re-drilled left-over 402 faceplates with a thin cosmetic overlay to hide the previous holes.
I do have the combined Fisher 80R subset w/non-Fisher dial glass + Ampex Preamp + Ampex faceplate (see attached photo and above worthpoint link). They are all in beautiful shape. I might consider a barter.
The 40W amplifiers are the only components I've gotten to so far -- This past winter I did a full rebuild on the amplifiers (as one had an AC hum - and for reliability considerations). I replaced all of the capacitors on both except for the ceramic discs. I used stock values -- but the capacitors I chose to use are physically very large (Russian FT-3 Teflon for coupling caps, polypropylene's for B+2 and B+3, and polyethylene with polystyrene bypasses for the output tube cathode bypass) -- requiring a chassis layout in Visio to help me figure out where things would fit. What once was a sparse chassis underside is pretty well packed now.
Upon completion I was surprised that one of the amplifiers still had the exact same AC hum. As we get towards cooler weather I will revisit them to consider the diodes and B+ delay -- as this is to be my living room heater. I think that all that's left to consider is a leaking diode in the voltage doubler circuit.
When you can, please share well-lit high resolution photos of the underside of each amplifier. I have a collection of underside photos and noticed that Ampex changed the grounding scheme between some of these amplifiers to accommodate physically larger voltage doubler capacitors. I will be able to better comment from there.
Hope this helps.
Bob