I´m also a fan of the Keith Scott Sound. Thea early records are like ACDC - two different guitars for a wall of Sound. Listen to the LIve Album from 1988 "live,live,live!". Great!
I´ve got here a Interview from 2004 - but in German........mmh.....
He uses heavy Strings - .013, .015, .018, .030, .040, .050 - don´t know, how he´s able to bend such strings on a Strat (Hello SRV?).
Effecs: Tube Screamer, Brown source overdrive from lovetone, Flanger, Rotosphere from Hughes and Kettner, Q-Tron from Electro Harmonics, Autowah with Distortion.
Guitars - Strats, Gibson and - Gretsch White Falcon! Also a Custom Guitar from Gretsch.
But ist not only the Vox Amp, he also played a Plexi Marshall.