Scotjute,
Bur oak is commonly used as a rootstock for most of the white oak group, because it is so readily available, and adaptable to a wide range of soil types & pHs.
I use bur oak seedlings mainly 'cause that's what I've got most readily available, and because they grow so rapidly.
There should be no problem with Q.alba(or any other member of the white oak group, for that matter) grafted onto bur oak understock.