Hi Nigel,
iirc there were some schemtics drawn by and Layouts with notes Like Larry, RYU, staalhoofd, levispecs and dukeampspecs in
MetroAmp some years ago, some links might be broken in the meanwhile.
as the discussion is still its clear that you've invested a lot of time in catching that AFD-tone, by getting the right "Levi"Speakers (somewhere it was assumed to be an G12h30 75 hz), NOS Mullard , "666Setting" and even contacting Mr Levi directly.
in Respect to Mr Levi and the other MetroAmp users who helped to lift that secret i can guess that you cannot give away the detailed specs.
I think on this forum there are also 2 threads SIR#36 & SIR#39 Mods which where based on the findings in Metro-Forum.
As these where from 2011 maybe you can give a rough update on new discoveries since then.
BR
Dominik