I would still do this at 55 LPI but print the black still.
Orange at 55-65 LPI with the black halftone knocked out, but on a low mesh, 110-195, hard squeegee, double pull, hard pressure to drive into garment.
Flash
Black WB or Soft Hand Plastisol (don't have to worry about dry in) at same LPI (inverse the orange image) on a 305 mesh, hard squeegee, single pull
You'll loose some of the halftones on the orange low mesh and have some gain, however you'll get that back with the black screen. I also like printing black on black.
Depending on the image it'd be fine with a single screen and low LPI as it can be a cool look, but if you want the best quality use two screens, one low mesh so you can get a nice bright discharge print, and one high mesh so you can hold high details and not have to sacrifice your image.
Cure for 3+ minutes, and this will be easily repeatable on reorders, as well as easy to run for 500 units as you won't have to be playing a balancing act.