I've just recently recorded a 5'6" 1976 Kimball parlor grand with a pair of 012s.
I used cardioid capsules: the treble mic I put just inside the curve of the case, aimed roughly at the the first harp rib at the hammers, facing the keyboard.The bass mic I put well back, halfway down the strings, over the second harp rib, facing the case under the lid: putting it up near the bridge or facing the hammers was too "klangy", for want of a better term.
I'm still working on my mic technique on that instrument- luckily, it is in my living room, and I have all the time in the world. Unluckily, is doesn't sound like *any* other piano I've ever recorded: so your mileage is sure as hell going to vary. Work with it- this ain't easy, and if it were, everybody would do it. Nobody has a recipe for your instrument or venue: I have also used TLM103s,
an Oktava MK319, and many other mics as well, with different pianos, players, and venues...
Your 012s certainly can give you a good result: but the final arbiter will be *your* ears, your judgement, and your confidence. Work with it, and enjoy the journey.