Aren't pin lock kegs shorter than ball lock kegs? In a pinch, you could replace the posts on a pin lock to make it into a ball lock.
I've gone to using the stainless QD's on my kegs, since they have the hose connections at a 90 degree angle relative to the post. This means less head space needed. I also use the 2.5 and 3 gallon kegs in my brew fridge (allows me to have four inside, on two levels).
BTW, looks like pin lock kegs are about 3" shorter and 1" wider/larger diameter, compared with ball lock kegs.