I've tried Neopan 400, Delta 400, and Rollei Retro 400 at box speed. C-L semi-stand. 1gr/l KBr, and 50-55 mins. They turned out OK, but maybe a bit overcooked, so Reinhold's recommendation of <40mins sounds closer to the mark. I started off with 3-4 inversions initially. 1 at 2min, then 1 at 4, 8, 16, and 32mins.