you won't find to many chinese pitbikes with 14" rears.
Like stated they are normally 12" rear but can get 14" fronts.
I'm a bit over 6"2 myself and i ride a Pitpro XR140 with no real troubles. I think you will find anything in the mid size (KLX style) bikes will be fine for what you want. Which one depends on your price range and what you want to use it for. Personally I would get a good base but try have enough left for some mods to make it suit you better. I got some pro tapers for my XR140 and it made a huge difference to how big the bike felt and I would never go back now.