Pretty nice results.
It's nice you came to share about your method.
I've carried on preliminary tests with little success.
I used slavich PFG 3m plates, developped in GP-2 at a strength advised by Bjelkhagen (15 mL of stock GP2 qsp 400 mL water for 15 min ) : the image is extremely light even exposing up to 8 min at f/4 at 11AM on bright sunlight.
You used lumière developper (pyrogallol + bromide) or GP2 ?