Definitely try some FP4 souped in a Pyro developer (Pyrocat for instance...) - I mean instead of fiddling with dichromate. I'm not particularty familiar with salt-prints but dichromate doesn't actually boost constrast with iron-silver processes I use; it just decreases the speed considerably, giving an impression of high contrast, with the inherent price of lowering the dmax...
Definitely try gold toning too!
Fix in alkaline sodium thiosulfate fixer. (Dilute the formula 1+4...)
Good luck & regards,