Century Ride in 2 1/2 months - Training?

I would imagine that doing weekday (4-5) rides of 15 - 30 miles and weekend rides of 60 - 80 should put you in good shape for riding a century.

Mix up the intensities during the week, throw in some intervals.  The intervals won't help you ride further but get there a bit faster.

Really you just need time in the saddle to finish a century, practice fueling for a ride that long, and making sure your position is good enough so you don't end up hunched over in pain at the end.

I agree, just start getting some longer rides in on the weekend and a few shorter during the week. You have plenty of time to build up the long rides. Get your nutrition settled and add a few hours during the week outside or on the trainer. I like to do some intervals early in a ride, then finish off the mid-week rides in Z2/Z3 to extend them out a bit.

To make the interval design easy, look at the hills on the course and determine how long it will take you to to do most of them. E.g. if most hills take less than or up to 5 minutes, design your intervals to be 5 minutes at Z4 and only do a few intervals. Don't bother going beyond 10 minutes, this gets into dedicated hill training efforts. If you're bored you can also do some 30:30's @ VO2max/120% FTP. These will help with group rides and rollers. Throw 10 of these in during a 1 - 1.5 hr trainer ride. Depending on how quickly you recover between workouts, I wouldn't do more than 1-2 interval sessions/wk. Soon you'll find yourself chatting up the hills while everyone else is panting.