265/70r16 is the perfect size for the 16" wheels. I would recommend getting the QD32 over the TD27, more power and better economy as the gearing is better on the open road. Loved my old r50. Stay away from the petrol versions, the QD32 has nearly as much power and way more torque.
Check the intake hose from the airbox to the turbo isn't cracked, mine was. $60 off trademe for a new one.
Also look for one that's had the electronically controlled injector pump rebuilt if you can
Stay away from any that jerk taking off from a stop as this can indicate the injector pump is on the way out. This doesn't apply to the wd21 as it has a mechanical injector pump.