I agree any wild blueberry would be worth a try to graft on to if grown from seed in it's final location. It would likely have a better
root system than a transplant.
However, the farkleberries are reported (link in the initial post) to have a much more robust root system and drought tolerance than blueberries. Since they are compatible as a rootstock, so long as the graft is done fairly low to the ground, the additional height of the farkleberry shouldn't be a problem. I haven't heard any reports that additional growth height is transferred to the grafted blueberry.
If you have access to the farkleberry seeds, please let me know. I would be glad to buy them.
thank you!
"Limitation is the mother of good management", Michael Evanari
Location: Southwestern Oregon (Jackson County), Zone 7