The absolute best tube set to completely re-tube your Marshall Super JH is below:
Maker: Watford Tubes England
Preamp tubes: Harma ECC83/7025 DRIVE TESTED "DR270" (Get the 270 rated version) These Don't need to be cryogenic tubes like the output tubes
Power amp / Output Tubes: KT66/HARMA-RETRO Cryogenic Treated
I had tried all the best tube types discussed here and there, vintage and modern, and i tried them side by side aswell, and these are by far, by a long way, which is hard to say these days, the best by a mile. This preamp and output tube "combination" is simply amazing. It is simply right! Remember, its the combination, not one or the other, even though they are amazing on their own, its the fact they are in the same amp at the same time, that's where the true perfection comes from. You will not be disappointed.
A Huge hint here: If you have the Super100JH, the reason you are in this particular forum ofcourse, then up-grade the filter caps with original ARS caps, they are cheap and easy to purchase from original maker in USA. The reason is, the new version of the exact same caps are higher rated and a stronger cap, sound wise, it will be absolutely identical, but you will have a stronger filter section by far in the amp. The filter caps take a lot of bass response beating over the years and the strength of this area in the amp actually does make a long lasting difference. Link to the ARS caps here:
http://www.arselectronics.com/ARSWEB/CapPage2.html
Also, amazing difference. Do an original Mustard cap job while you can still get NOS mustard caps off ebay. The tone is transformed. The original Marshall hum, very slight, but indicative of differences in tone is back. The caps that this head came out with are one of the very highest quality, fantastic, but their dead quiet nature also effects the tone of the amp, as its all in the circuit, the hum, and its their for a reason. This has nothing to do with the transformer hum, completely separate thing. The Mustard caps bring out some subtle yet radical tonal differences, and its that much closer to what you would call the hole grail tone in this amp. Combined with the above tubes, and you "will" agree that something very astounding just happens to the amp. :-)
No need to change other caps and resisters etc.
P.S. Run your system through a Furman Power Conditioner! JUST DO IT! They are not expensive, but power line noise and tube longevity is substantial. DO IT!
Enjoy!
:-)