I have an opportunity to buy this beautiful acer very cheap.

I suppose it was originally an acer shirasawanum grafted onto regular green leaf acer palmatum rootstock. Probably it was neglected for a long time because rootstock was allowed to outgrow the scion - acer shirasawanum.

I know that in such situations scion tends to loose vigor and eventually die off, however I am wondering if this is the case because both parts of the tree look very vigorous.

I am wondering if I could air layer the scion - acer shirasawanum (trunk marked with red) and after it puts down the roots I would cut the scion from the rest of the tree. Would this affect rest of the tree. i.e acer palmatum rootstock?

Many thanks for help