Road Cycling - Need help training for this one....

I have registered to ride a 60 mile (100km) ride on April 3rd.

Although I am riding for for a couple of years the longest rides I do are a 35 miles loop with only 400 ft total vertical climb (takes me 2.5 hours net riding time).

The ride I have registered for is Tierra Bella Bicycle Tour (http://www.actc.org/tb/) described as:
100K (60.7 mi, 2065 ft) (http://www.actc.org/tb/route.html)
This flat to rolling route begins with a morning circuit around Uvas and Chesbro reservoirs, followed by a brisk mid-day climb to Gilroy Hot Springs. You'll round off the day with a descent down Canada Road and a tour through Gilroy to return to Gavilan College. Rest stops are about 24 miles apart.

I am 51 yrs old, weight 210lb (I'm a weight lifter), and in OK shape.. What would be the most officiant training program to ready my self for this ride (one month only)??

You have about a month. Here's my free advice (It's worth every penny): The distance shouldn't be too much of a problem. You're already over half way there. Start hitting the hills. Pick a hill that is challenging and see how far you can make it up without stopping. If you do that about three times a week you'll be surprised at how much you can increase that distance in three weeks. If you alternate that with some flat longer rides, you shouldn't have a problem. A week before the ride you should start cutting down on your training. Get at least one or two rest days a week. During the ride, don't go out too fast. Pace yourself. If you have to, walk up the hills. Nobody is going to criticize you. (At least I won't)

Good luck and have fun.

In addition to more hills, you might practice the 100k route you intend to ride. At least, you will have an indication of any potential problems.

Thanks... I was afraid you'd say that (3 times a week on the hills) :) but it makes sense..

Agree on the mileage. Did an MS150 last year and my longest ride was 60 miles. Did 85 on Day 1 with little trouble. Hardest part was a pretty steep, 1-mile incline. Hit the hills. If that isn't feasible, I'd suggest riding in a higher gear and standing up more often to try to simulate the difficulty of a hill. As for riding the route in advance, GREAT idea (though it might be discouraging). If nothing else, drive it. You might also got Topo USA 4.0 (if you can spare $100) and map out the route to see an elevation profile.