Just a note, unless you can easily remove the existing bearings without applying any significant force on the outside race (such as through differential cooling and heating, without overheating the lubricant, or applying force only on the inner bearing when removing it from the existing head) it is often better to just go ahead and plan on replacing the bearings rather than trying to reuse them as they are not terribly expensive.
As a rule you don’t ever want to be transferring force from be race to the other via the ball bearings or you can distort the races which will damage the bearing after awhile since the bearings are much harder than the races.
So if I were taking the project on, I would simply go out and buy some new quality bearings for the new Shelix cutter head and go ahead and leave the bearings in the original cutterhead and pack it safely in the box in case I ever need to temporarily swap back in the original cutterhead or if I wanted to move the Shelix over to a new Jointer in the future (you can then sell off the existing jointer with its original cutterhead in place, for example). I would also select shielded bearings over open bearings to help keep the dust out of the new bearings (at least shielded on one side, the side facing the cutterhead, if not both sides).
