you could run a 45 safely stock with some plugwires and plugs (make sure you ignition system is up to par, ex. cap,rotor,coil ect.) to run a 55 safely ALL YOU NEED is a ignition system and copper ngks.
i suggest jacobs by far has some of the best products a little pricey though. i don't suggest ANY NITROUS SYSTEM, and if you are spraying use a fukin IGNITON SYSTEM. (also don't use a dry system, zex sylinoids freeze up alot you should of got nx wet/dry system or something of that nature)
Anthony