Great work Marc! I have a few observations/questions.
What unregulated psu clamps/cap are you referring to (the 10k uf caps?? Aren't those mounted on the pcb?). How would using the stock 10k and 3.3kuf caps be cutting corners? Is there evidence that more capacitance is needed here/beneficial... based on rules of thumb, or precedent from other similar projects? Any downsides to putting in bigger psu filter caps?
Can we include a nice power indicator led or two? Blue or violet color
Three values of loading resistors/caps (at least the most popular ones 1k, 47k, other? 0pf, 100pf, other?) along with selector switch(es) for that purpose? Could be done manually in the box if necessary. Just a thought.
Is the diode bridge a soft recovery type? Can it be? Does it matter?
Will any of the 1.5" tall heatsinks fit/work? Trying to fit into a 2" tall case, if feasible. Same comment for the large caps.
Cheers
Pete