Anything less than 100% ideal conformation????? Are you serious? This sounds crazy to me, but then I am a part of the Arabian halter world. Breeding 2 year old colts is very common (provided he's mature enough) because, as we are breeding for halter, at 2 y/o we can see his conformation. That's his "test" as a potential sire. And what horse is perfect 100%, conformation wise? I've never seen one. That's why we breed. To create the perfect horse. I'm not saying that's what the OP's reasons are, but those are mine.
And honestly, not breeding a mare that is over 12, just because she's "too old" is baloney. Mares can reproduce and birth healthy foals up into their 20's. I suggest to the OP that he get a vet out and do a reproductive examination to make sure that the mare's uterus is healthy (not pooling urine, no big cysts etc..) and if the vet pronounces her breeding healthy, then I would say that the mare will be fine.
Now, after that is all said, I don't think that breeding just to breed is very responsible, but that is up to the owner/OP. I can understand the emotion of wanting a foal out of your stallion/mare. It would be a lot easier to buy a yearling, though. It's up to you. What was your mare retired from? What will you be doing with this planned foal?
A good horse is worth more than riches. ~ Spanish Proverb