The rim and head size on the .30-06 and the 8mm Mauser is exactly the same, thus the bolt face will be the same. In fact, I make 8mm brass from .30-06 brass. Though there are some small ring 98's, most 98 Mausers are large ring and provide the preferred action for custom rifles. Mausers such as the 93, 95, and 96 are small ring, and though strong, they don't have the safer gas venting system that the 98 has, should a case head ever let go, though that is not a common malfunction. The 93, 95, and 96 are also cock on closing which seems to be less desirable for a custom Mauser. The 98 action you have should be suitable for your conversion once checked out and approved by a competent 'smith.