The "Series" Paramounts have racing geometry with short chainstays and I don't think they have eyelets for rack/fender mounting. Any bike in a pinch is better than none, but you'd be better off with eyelets so you can mount a rack, and longer chainstays so you won't be hitting the panniers with your heels. There are too many of those around to make a specific recommendation. IMO, you just happen to have run across one of the least suitable frames for your purpose.
The chainstays will be short and there more than likely there will not be any eyelets for rack/fender mounting. That said, Paramounts are sweet riding bikes. Below my 1972 P-15 that I commute with in the summer. It was the touring model.
Miyata 210, Fuji Royale II, Bridgestone Kabuki, Miyata Ninety
I *think* the frame described would have been built overseas. That said, they're still nothing to sneeze at. But at that price, I'd scoop up the frame, flip it on eBay, and use the obscene return on the $50 to pick up something more commute-worthy. It's probably worth posting the details to Classic & Vintage or here on the Schwinn forums to get info on the frame.
It's not only a bad idea, it's a sin. What year is the frame? $50 for a Wisconsin built Paramount in good condition is incredible (if it is these things).
I'm pretty certain the "Series" Paramounts are TIG-welded and from Taiwan. They're OK frames, but they're not the collectible Waterford-built product that ignites bidding wars on ebay. $50 is a good deal on one, IMO, but not a screamer.