I don't know a dang thing about Pinarellos, but I looked into buying one awhile ago, and ran across a fellow on the Road Bike Review site that had fair knowledge. It may pay to poke around there for info.

Judging from the pictures I would hazard a guess that your bike is not top of the line, but near the top. Chrome on the chain stays is always a good thing. Feel inside the tubes from the bottom bracket to see if it's SL or SLX. I would guess it's at least SL. I would tend to agree with marengo that it is a Treviso model.

I've yet to see a vintage Pinarello with good original paint or complete decals. When I was active back in the early to mid 80's Pinarellos were considered to be a second tier bike, but that may have been snobbery in my locale. In any case it looks like a fine bike and I'm sure you'll enjoy riding it.

I doubt us mere mortals could tell the difference in ride between a De Rosa and a Pinarello in any case.

Also, it appears your drop out screws are in backwards.