first century in 3 weeks

[chicagogal]

The local bike club is hosting a well-supported century with the option of a true century or a metric century.
The event is in one month and I am not sure what to plan as far as training.
After a couple years of little to no cycling, I took it back up this summer. I ride 25-35 miles 4-5 times/week. My longest ride so far has been at 40 miles. I probably can't get a long ride in for 1.5 weeks due to family obligations, but I will keep up my ~5d/week routine. I plan on doing at least a 50mi bike ride 2.5 weeks before the event.
The course is mostly flats (which is also what I have been training on).
Is there any way to get ready for the true century in this amount of time? Or should I settle for the metric this year and aim for the century next year?
I should also mention that the start of the ride is 8mi from my house, which adds 16mi to whichever ride I do in order to get home.

[Biker Jo]

Hey, Chicagogal, you're not talking about the North Shore Century by any chance, are you?

[chicagogal]

Yes, that's the one. Are you riding it?

[Biker Jo]

I'm actually a member of the Evanston Bike Club, so I've been doing volunteer work for the ride, but I am planning on riding.

It sounds like we may be almost neighbors. Send me a PM if you want, or I'll do the same!