Just 5 days? I would not recommend that you do anything strenuous with the century so close unless you recover really fast. I don't think that with just 5 days that you can really achieve anything by doing training now. Just go out and do training rides.
The rule of thumb for rides is you should do a ride of 70% your target distance in training. Your 50 mile ride sounds like a good tuneup. Just take the century easy and ride within yourself. Go a little slower than usual. If you have energy to burn, you can use it on the last 20 miles or so.