Virtuals are misleading in the real world. What is likely to happen is you will get the trees out of the containers and find there is no real good way to get them close enough to the rock to make things look good. Root masses on trees that old tend to be rigid several inches out from the trunk
To get them to adhere as closely as the virtuals will likely entail removing and/or damaging the roots enough to kill the tree
That is unless you’re lucky enough to have one that has an unusual enough root mass that is flexible enough to get on the rock without looking too ridiculous
Root over rock trees are typically planted over rocks as seedlings when their roots aren’t developed. That development takes place ON THE ROCK as the tree is developed. This treatment allows the roots to adhere closely to the rock and fit the rocks contour naturally. If trees with even slightly mature roots grown in another container are used there is always a gap between the bottom of the tree and the rock
Fingers crossed for you. Good luck. The ultimate decision on which tree you should use will be determined by the above probably not by your choice.
It is but it's also the challenge to create something believable. I got the inspiration for this project when I scrolled through the bonsai-hunter shimpaku gallery. Some of the best shimpakus and rock plantings I ever saw