That is a very interesting and nice looking CZ 75. I cannot help with determining if it has been refinished. However, it appears to be a 1982-1983 CZ 75 based on the Made in Czechoslovakia mark on a single line and the safety having the second larger hole in the middle.
The pistols of that time were blued and not painted with the later enamel like finish starting in 1984. It's a nice blue on these older CZs but nothing super special. Even if it has been re-blued, as long as its nicely done and still in excellent condition, that is what would matter to me. I would love to shoot it in that caliber.
Good luck with your purchase decision. If you do buy it, give us an update when you receive it and on how it shoots.
Edit - When I shoot the older models, I replace the original "waffle" grips and the slide stop with newer versions to preserve them.