On the two step, get an adjustable dial one for your rpm variance as in below 4500 I believe. We use the over 4500 one.
Install two line locks, one on the front system and one on the rear system. Maybe a dbl pole/dbl throw switch on the front one to use for burnouts, and switch to both for staging/starting line holding with all 4 wheel brakes. Also install a brake system pressure gauge in front or rear. I use rear as I used to have a 5 speed and would use it for staging because car would settle down good. Use the same pressure all the time to keep car consistent.
I use a micro switch mounted down by the shifter, actually I have two, one short throw the the other with .250? throw to slow down launch time.
I get them from Graingers. The dk brown ones 3/4x3/4x2 1/2 long, two 8-32 bolt mounting holes, NO - normal open, NC - normal closed, Common - I use for power to switch and NO wired to TB, LL, (Rr brks, Frt brks through frt brk switch), 2 step.