http://www.acoustica.org.uk/
You'll find Nait2 mods here.
I'd try to stick one of Les's TPR4s into the Nait if space allowed, otherwise Teddy superregs.
After 30 yrs no doubt they need a recap, generally you could say the lack control over what is happening big time with old caps.
You'll realize if you do one of them, the other one virtually seems dead in comparison.
@ James: with more efficient speakers a Nait might be enough,
with Kans (and I can only recommend on what I know here)
I definitely suggest 72-HC- 140 as a great symbiosis,
but even a 250 size amp or double monos will get you wake up the Kans into even quite more stunning presentation.
May not apply with more efficient speakers, but with a Kan you may get used and be ok with a Nait2 presentation.
One you ever tried some 140 or above amp on them , you realize they have in fact been in 'sleep-mode' on the Nait all those years.
Once heard, there's no way back, the Kan LOVE beefy amps.
And before I'd not give a HiCap to a 72, I'd rather let go of separates entirely and choose something like a Rega Elicit R integrated ..or Nait if you like, but I imagine Kans could well favour the additional bizeps the Rega Elicit R offers..?