If you dig these you will NOT wind up with super trees. You will wind up-if they live--with a lot of bare trunks with foliage at the ends--very hard to make into bonsai without extensive bending (which isn't easy if you don't know how to do it), or extensive grafting of foliage on those huge bare stretches.
this is NOT great material, unless you've got some experience under your belt.
BTW, new top growth doesn't mean all that much for larger collected trees. Older trees can push new foliage without putting on new root growth (which is where new growth actually counts in recovery). Older trees like these can push new top growth from simple momentum and stored reserves.
Sure dig them if you want to learn aftercare for larger yamadori. Don't expect bonsai from them any time soon, or at all, though.
This sounds pessimistic, but it's not. It's realistic.