I would call Compucar.
Otherwise it will be tuned by fuel pressure so if it was me I'd put both plates on one solenoid for each side (n20/fuel) of the system and start at 5.0psi and do a short test hit. Due to the lack of jets you can't really change the nitrous to fuel ratio much other than by adjusting the pressure. Once you get a handle on that you can start bumping the timing back in. I'd be running some 110 or C12 and start around 22* total advance.
As far as the "HP" rating of the kit, it's hard to say. Either way you are adding x amount of fuel/nitrous x 2 so yes it is additive in a linear fashion. A true "200hp" nitrous shot will definitely get your attention. Don't be surprised if ends up making more like 250-300 hp if your combo like nitrous.
For the solenoids I'd uses whatever they offer for the NOS Big Shot or Race Fogger. Definitely go with -6 lines for future expansion.
I did call compu Car. They weren’t very helpful considering it’s an “obsolete” system
I get it- a tunable plate would be preferred....
I think i get what what you’re saying -the plate is fixed- give them the biggest flow at the solenoids you can (such as the big shot)