Polo Bikes

short pull disc breaks? I didn't know such a thing existed, I thought they were all long pull?

sheldon explains both the long pull with short brakes and vice versa, look at too much/too little mechanical advantage:
http://sheldonbrown.com/rim-brakes.html#ma
basically either get a travel agent (you can fit it in reverse in your case) or disc brakes that are long pull?

Avid BB7 Road Disc Brake Caliper

Specifications:
• Caliper Type: 74mm Post Mount
• Brake Lever Actuation: Short Pull
• Hub/Brake Compatibility: 6-Bolt Disc

Thanks for the Sheldon link, I'll have a look.
Might try and get an MTB disc caliper.