Why would you want to lower the dose that the doc gave you, especially since your going for performance enhancement with it? I would take it they way it was prescribed. I doubt you'll have much trouble with painful pumps at that dose. Unless of course you had the in your youth, b/c your test will be about where it was when you were 18. Plus it sounds like your doc basically prescribed you a cycle. Are you supposed to discontinue the test after the 10 weeks? Or maybe lower the dose at that time?
Rocco had a good point that endurance sports, where extremely high reps/training is involved is almost sure to cause your natural levels of test to drop. Taking exogenous test will keep that at the normal levels no matter what type of excercise you do. This could be one reason you've heard of them taking an Hormone Replacement Therapy (HRT) dose of test. I've also heard of many in these sports taking low doses of nandrolone (usually decaonate) in order to help with joint pain/stiffness.
If you feel the need to stack anything with it, I'd go with the Tbol and stay away from the Winstrol (winny). Winstrol (winny) has a tendency to make joints/ligaments very dry and susceptible to tearing or sprains. It also causes pain in the joints that I'm sure that you could do without if you are running long distances regularly. The Tbol will give you much the same effect, exept it's more androgenic and can lead to mass gain easier than Winstrol (winny). But of course this is dependent on your diet.