Krav risks becoming the new taekwondo. You can't fling a cat in a strip mall without hitting a TKD school (disclaimer: I have red belt in tkd). I've trained in self defense systems. I think jujitsu is a good base art. What I don't like about jujitsu and judo is they train barefoot in a gi. That's not real world, and the gi, in training, is used as grab leverage against the opponent. Grabbing a t-shirt isn't the same. And it's usually a one on one training, ignoring multiple opponents. But you can't always choose exactly what you want. Kickboxing and Thia box on top of jujitsu.
8 weeks of training is not enough time. With only that much time to spend you're probably better off stripping the training down to just boxing. There needs to be some in-the-ring (whether judo, jujitsu, Thai, TKD, etc.) mixing it up to develop the self confident belief that he could use whatever it is in a fight and know his limitations.
If he's not very athletic to begin with learning a MA isn't going to be much help against a more athletic opponent. You'd be better off spending the money on a good weight trainer and get him started on beefing up first. Just my opinion.
Would I be putting a grain-feed cow on a fad diet if I took it out of the feedlot and put it on pasture eating the grass nature intended?