My concern of grafting high on wild root stock would be blight killing the rootstock.
If the scion wood is blight resistant , I would think it would be better off to root that as a cutting , layering, or graft Union buried , so that the whole new plant is resistant,
If grafted onto a wild seedling of unknown resistance , blight could kill the rootstock and you have lost it.
I "had " an incredible planting of filbert / hazel cross, I gathered seed from the infamous "Etter " nut orchard (with John Gordan ! )in Pa.
Planted them on the farm here , 5yr started Bering , 10 yrs , of heavy production, some 15 ft. Tall ,beautiful , though much variation then … Then the blight.came…within 5 yrs or so it killed them “all”.
I was , and still am really bummed about it.
So hopefully this info may save some of you about 20 yrs.!!!
These trees had a mostly European “look” to them, of unknown ancestry
As Mr Etter had past befor I got a chance to visit.
Now I am starting some of the new blight resistant ? Ones. Starting over again .