I mean what's your plans with it? Are you wanting to bonsai it or keep it as a decorative yard tree? Usually grafts, unless done really well, aren't ideal in bonsai. I made the mistake when I was first starting out of buying a garden center JM that was grafted, but decided to keep it and have it in a really big pot to plant when we move into our first house.
If planning to bonsai, you could always air layer above the graft later down the road. Either way, beautiful tree!