Jessf
Mame
the graft is close to 6" above the soil line, that's not too hight? The picture may not do justice to the size of this material.
Have you explored below the soil surface at all? I won't be surprised if you find a several more inches of featureless trunk before you get to any good roots (and maybe even reverse taper, I see some hints of that just above the soil surface). You might very well have to do a ground layer (wire tourniquet) in that case.
Having not worked at all with grafted trees - does anyone know what will happen when branches start growing above (but close to) the graft, but not below? Will that taper tend to disappear, or will there always be a swelling below the graft? Wondering if it might be smart to allow a couple of branches to grow from below the graft to serve as sacrifice branches to help preserve the taper (assuming branches sprout in that area)?
Edited to add - regarding ground planting - here in zone 6 western NY I've had almost 100% success with trees, shrubs, perennials planted before June. In contrast, I've lost lots of things planted later in the summer or fall. I think June is a grey area...normally I think it should have time to root in well, but consider that you've chopped off all the foliage so for now there's no photosynthesis to help re-grow roots. I'd be inclined to keep it in the pot for another season, or provide extra winter protection if I planted it in the ground at this point.