I read his first Modern Drummer interview back in the 70s and he said he had a number of Gretsch drums, Ludwigs, Slingerlands, Camcos....I don't think his association with Pearl happened until after the Toto Hydra album - because he was playing some clear Ludwig Vistalites in the videos to promote that album. But he did say he used a Slingerland kit with a 28" bass drum on "Lido Shuffle".
I have this feeling he played basic 5-piece drum kits back then since having a 10" rack tom wasn't a normal thing yet. And when he did settle in with Pearl, it looked like all he did was add the 10" tom to the standard 12/13/16 configuration for the advertisements, anyway.
Most of the time it was 12" and 13" toms, and a 16" floor tom. Usually with the bottom heads removed too. When I saw him live at the Baked Potato, it was a Gretsch set, with those sizes, and bottom heads removed.