The height of the bearing mounting block will vary according to the bearings used. Each maker will have to determine his/her own measurements. I just happened to use Browning 3/4" bore VPLS-212 pillow block bearings as I found a good price on a pair of them. I also liked the better finish of their cast iron.
I decided to go with red oak for the bearing mounting block as the original maker used 3/4" plywood, and I try to avoid setting screws into the end grain of plywood. Any suitable hardwood will do. Also, I prefer the white oak to red oak as red oak has microscopic hollow tubes going through it lengthwise - it absorbs and retains more readily liquids such as oil, water, etc.; however, it may be easier to find red oak locally as opposed to white oak, and given that sanding is basically a dry operation red oak should do just fine. Price was also a factor for me as Home Depot had a special on red oak - about half the price of that of the local lumber yards.