ID, I wanted to explain a little more about where I'm coming from in my posts. If I seem a little stubborn at times, it's because I have had the privilege of learning from the best. As I stated before, John Cook was my college coach. I'm assuming you know who he is and what he has accomplished, especially in the last few years. There are lots of reasons for his success, and I'm sure there are many that I know nothing about. But there are some fundamental processes I learned from him that should be noted here (sorry coach, gonna give some of your secrets away):
1. Training is inexact, imperfect, and a series of compromises.
2. There is no understanding a workout until you understand both the benefits as well as the costs. Every workout is both a step backward as well as a step forward.
3. By understanding proper post workout recovery, a bigger step forward can be attained.
4. By understanding and respecting the breakdown aspects of every workout, a smaller backward step can be taken.
5. Long term thinking will prevail. Building a solid foundation allows for uninterrupted serious training in the future.
You really are ahead of schedule, ID. You got there because you are doing a lot of things right. I'm guessing you didn't actually put your PRs into the age grade calculator before you created this thread. Was it a shock when you realized you were going to have to run 5% faster age graded now? That you were going to have to be almost world-class?
If you follow any pre-written training plan, it might provide a couple percent gain to what you accomplished as a 20 year old. But if you really become a student of the sport and apply it on a daily basis as Pete Magill does, I think your odds will go up considerably.
I think you will end up doing this, accomplishing more than you ever expected, and quieting the naysayers on the first page of this thread. Forgive them though, for they knew not who they were dealing with.