As a former PInz owner, always check it out if you don't know the PO. The 710K is a formidable vehicle and can surprise those that don't know about pinzies with the vehicle's capabilities. Without knowing the age, 23K does not sound out of reason if it has been taken care of.
edit: Just checked it out on BAT. The trailer is included! My word, what a beautiful vehicle. Even though it might require a few little items to be pristine it is a gorgeous vehicle. The spedo is in kilometers and if accurate it is very low milage for a 71.