9 inch hubs?

Does it have good studs both left hand and right hand ? Maybe you have ruined them w/ the hammer already but if not, the correct cutter might be a better plan.
The drum will absorb the impact. To beat them out requires supporting under/ inside like with a piece of thick wall tubing surrounding the studs head.
Now would be a great time to atleast consider the Scarebird conversion or other disc brake conversion.