Training at 50

I've been reading a lot here about the different training programs and now find myself wondering what I should do.
A little background. Twenty plus years ago I was picked up by a local team. The team consisted of some younger up and coming racers (mostly from a junior RR team) myself and another guy my age (27 at the time.) I had the most work to do in order to be able to keep up with the group. The coach wanted me to stick to the sport class for at least the first half of the season.
The training was hard and did wonders for my overall fitness. Since I had only ridden mtbs up to that point I did have some advantages over the kids when it came to technical off road training.
Anyway, my results were great and I had planned to enter a mid season race as as expert. I guess my goal was coming to fruition. But then a knee injury along with a prolonged illness ended my racing days. Frustrated I just quit riding altogether....
Fast forward (with some details deleted. I had tried a couple of comebacks..)

Last year my son and I got on some borrowed bikes and really enjoyed it.
To make this long story short, we both started racing, and although the boy has had to back off a bit (senior year at UCSD school of engineering) I continue to pursue the long ago goal of reaching the expert class.
Now approaching 50 I have other physical issues that keep me back from training as hard as I would like.
My knees are fine now (only three operations on them) and I've learned some great stretching exercises that keep all my joints nice and happy, save one.
My neck. I can't really spend the time on the bike I would like to before my neck starts hurting. It really isn't much of an issue on the mtb as much as it is on the road bike. When talking to people who 'fit' bikes to riders, I'm not getting the impression they have any real understanding of the issues involved. So I just install some riser bars on the bike (1.5") and keep to a large frame (I"m 5'11")
I've talked to a couple of other old guys and apparently it is a common issue as we get older. I've had the neck looked at by a doctor and had all the tests done. There is nothing that needs to be done (it doesn't need surgery and it won't get any worse, apparently it is residuals from an old motocross injury.)
Now lets get to the point of this thread.
Does anyone know of a training program that might have been developed with my type of situation in mind? That is to say a training program that is age specific? And one that doesn't include a lot of road work or long hours on the bike at a time.
Any suggestions would help.