There is no "market" for pure stock. Not yet anyway. There sure isn't one for modified, either.
You bought it for a reason. You didn't buy it because, oh, I wanted a V6 Buick Regal with 34K on the clock. What was the reason? If it was because it would be a fantastic base for a modified car, then you struck gold because it certainly seems that you did. If you bought it for a weekend cruiser just to tool around in for cheap, then it will do that too.
At any rate, find you some fillers and paint/install them, as you will probably need them no matter which way you decide. Once you get the car road-worthy, you have time to set your goal for the car. Leave it as is, or if the Buick was the car of your dreams you want to mod out and make a street monster out of, then do it. You will likely be cutting something somewhere once you start modding, so get the idea of keeping the stock crap you pull off of there out of your head unless you just do some suspension and wheel mods or what not.
Do a little or do a lot, you've got a great canvas that nobody has messed with....yet. 🙂