Back in '86 I bought a new XL600R, which I put about 14,000 miles on, a combination of on and off road. I am not familiar with the XL600PD, but I am guessing it is similar mechanically to my XL600R with Paris Dakar bodywork.
The XL600R was an excellent, very versatile dual sport bike. However, it had one problem: temperamental starting. Everything from the valve adjustment to the compression release had to be adjusted perfectly for it to start. The worst thing was if it stalled before completely warming up, good luck ever finding the choke setting to get it started again. Since I have minimal patience for bikes that are temperamental starters, I would not buy it unless I had the opportunity to start it and ride it a short distance several times, and felt confident about the bike's starting nature.