How much nitrous for a stock piston?

I have a dedicated fuel pump for it, and the engine is in excellent condition. Very very good. I have holley strip annihilator ignition, but the only retard function is startup retard up to 20*. I have the rpm switch set to kick it on at 3400, I wonder if an msd boost timing retard would mess up my holley ignition, I have a second rpm switch I don't use. In the manual for the ignition it claims using any ignition product other than holley with it could blow it up. I would want it to drop 5 or 6 degrees.