I would recommend learning your chosen MAs separately to a degree of competence before bringing it together in an all encompassing mma class. Trying to learn everything at the same time would lead to confusion imho.
Not tried Kempo, but Krav Maga is the -real- Israeli defence ma (and has been adopted by most militaries and law enforcement specialists around the world). Many of its 'moves' are illigal in mma, but its main strength are its philosophies of absolute and pre-emptive aggression utilizing minimal defence. It's teaching techniques are also unique and useful.