You can help a pup reach their "potential" drive through tug work, drive building exercises using food and toy, and endurance training - but if it isn't already there genetically, you can't make it appear.
Kind of like those athletes who were just born to do their sport. Anyone can practice, train, work hard, be committed, but they may never reach the same level as someone who was just born with all the right qualities to do it.
As for the tracking, I want to see a dog with a lot of drive and a CLEAR head on the track, not a "calm" dog just moseying along. But a mid-level drive dog, is perfectly capable of tracking, and some lower prey drive dogs would be good too as long as the food drive is there.
Now, if you want a companion and someone to explore ScH with, then there is absolutely nothing wrong with getting a calmer dog, who is a companion first. Especially if this is your first Shepherd. If you catch the "bug" and need to do sport at a competitive level, you can look for that dog then.
If you know that NOW you need a dog to compete with, I would not go with one from untitled parents. Not saying that a dog from untitled parents couldn't have the drive, but just saying that someone who has gone through the process of training and titling dogs will have a better knowledge of what could qualify as a working puppy, so may be better able to place the correct pup with you.
Also, if the pups haven't been "tested" for drives, then seeing them "off" could be deceiving. When I got my male, I had asked for a competition dog, possible breeding male. When I first saw him, he seemed so "tame" compared to my female when she was his age. I was a little taken aback, as this was a pup the breeder had held back for themselves. So I walked him a bit, did a little bit of VERY basic OB. I asked her if she thought he was TOO CALM for competition, she looked at me like I was crazy (My female, from DDR lines, was incessant as a puppy, needing 4-5 hours a day of exercise and OB, and even then rarely slept). She layed him a food track, and I watched this amazing 4month old pup pulling, digging in and pushing his nose into the ground for that track. Then she grabbed a tug and set up a helper, this dog went from zero to 60 in 1.2 seconds.
So I learned that there are Shepherds with an "off switch" LOL
Either way, he is an AMAZING boy, with a hard, fast grip, EXTREME Object and prey drive, good defense drive, good hunt drive and great endurance....then you tell him to lay down and he will shut off and do his best to impersonate a rug....LOL
Good luck with your new pup!