I'm glad to see your primary focus is long term. I think one of the advantages we have as masters runners, is the ability to look back on our mistakes as young athletes, and make more realistic goals. Patience is a key element, which I didn't possess as a young runner. I've always had a good work ethic, and that is what always got me into trouble. I was way to aggressive. I didn't have a good grasp of the various intensities of training that would make up a solid training program.
When I started running again (walk/jog), after a 13 year layoff, I was pretty pessimistic, about my chances of being able to run more than 20 mpw. For the first year, I was super cautious on the distance and intensity, and wasn't really to worried about running fast races. I was shocked to experience injury free running. It wasn't until I starting training to race fast, that I had some issues. That is where having a good coach comes in. Someone who knows your background, strengths and weaknesses, and can come up with a plan that brings you along at the right intensity, with a more objective perspective. When I hired Tinman, my workouts actually became easier as far as intense running. For the first couple of months, I wasn't sure this more moderate way of training would work, particularly for shorter distances like the mile and 800 meters. But I knew this type of training was sustainable for a long period of time, so I wanted to give it a shot. Between three and five months after hiring Tom, my time dropped significantly. It was surreal. I am still amazed with the concept of how running more easy miles, along with very controlled CV pace, tempos, and sprinkling in some fast striders, can create such an improvement compared to running more intense race pace (mile & 5k intervals) in practice.
So, as I see it, you have a couple of options:
1) Read through previous posts on this forum. This is one of the best, if not the best forum on training/racing. Most of the participants here are very knowledgeable and have been implementing the "Tinman" training for quite a few years, and have great insight to the details to this way of training. I usually check this forum out a couple of times per week, just to stay fresh with the concepts. Many of the posters, are coaches and/or personal trainers. Do this option, if you want to race fast!
2) Hire Tom as a coach, and let him figure out a customized plan, and guide you through the process. Reading about some of the concepts, and implementing them are two different things. At the very least, do this until you understand how to train with the correct intensities, and understand some of the details behind Tinman training. For me, I never could have transitioned to this kind of training without someone to lay it out for me. I just wouldn't have had the discipline to believe it would work in the long term. I probably would have tried it for a couple of weeks, and gradually transitioned back to the more intense way. This is always my choice, as worrying about a training plan seems like to much work, especially when trying to balance family/work/running. Do this option, if you want to race REALLY fast!
BTW, my first mile back after the 13 year layoff was 5:44. 800 was 2:35. 5k was 21:50. I was 46 at the time, so your ahead of where I was at the time!