Hi Sigma7 - and sorry for the delay!
I unfortunately don't remember my settings - but here is what I would recommend to get a little closer to Johnson's solo sound on a standard set-up. (Johnson uses more amps and effects than we what is apropriate!

)
Try to roll of quite some treble (try both on your amp and guitar). Then go for lots of distortion (that works on my amp which is high gain - but nothing extreme).
Also - try exagerating the middle and bass settings - more than you usually would.
Hope it helps! Oh I have never really got very close to Johnson's sound - so you should probably check with other people as well..