Upload & Sell: On
Well, as you said the intent was to grab some nifty clouds to drop in another photo later. Play if you like, but I wouldn't worry too much with trying to correct the entire image.
If you plan to make a sky catalog, be sure to notate the details of each photo, including time of day, date and compass position. That way you can match to your needs and come up with a more realistic looking composite.
The architectural photographer Julius Schulman had hundreds of negatives of sky and lawns, since he often had to shoot before landscaping was finished.
Great tips Doug - thanks! I would never have thought to keep track of details to match images.