No one really knows what the "most effective" cycle is because no studies have been done comparing all the various AAS at equivalent doses at different intervals.
Also, just because a steroid is good at increasing RBC count does not mean it is good for increasing endurance. Tren can increase RBC count quite a bit, especially at higher dosages, but try running a few miles on that. Good luck.
While Anadrol won't decrease cardiovascular capacity like tren and is great for increasing RBC count within a short time when used at higher dosages (150-200 mg/day), loading up on a bunch of Drol is likely to impair endurance performance, as the concomitant weight gain can be substantial. Anytime you add 15-20 lbs of bodyweight, it is going to adversely affect endurance, thereby canceling out many of the benefits imparted by the increased RBC count.
Ideally, you want a drug which is good at increasing RBC count, causes little to no weight gain, and does not negatively affect cardiovascular capacity.
Being that you have such a short time, high dose Var (100 mg/day) used in concert with high-dose bold ace/prop (800-1,000 mg/week--if you can handle the short estered bold) would likely provide considerable benefit.
Keep in mind that I am not recommending this (I would never recommend a cycle like this without first consulting with the individual), I am simply saying it would be effective given the short time frame you have to increase RBC count.
Of course, EPO is the best choice, but you need to know what you're doing or you can hurt yourself. Like insulin, diuretics, or DNP, taking too much EPO can potentially kill you. This will never happen with AAS, at least not within 3 weeks