you'd be better off just running a complete 170 setup for starters - sack the mondingo callipers off........ loads of different pad choices then.
ST150 and ST170 are the same callipers (just the carrier bracket which gives the extra disc size on the 170)
i run 15" wheels on mine, but they're aftermarket. There's quite alot of meat in the callipers - you literally just need to shave the outside edge down a little. I've a few friends who've had to do it to fit 15" team dynamics wheels