I crowned the muzzle on the 30-06 rolling block I made with a RCBS deburring tool! It shoots just fine. Remember, as long as the end of the barrel is squared to the bore, you don't actually need a crown at all. Crowns are put on barrels to protect the rifling in the bore at the point where it ends, should the rifle's muzzle hit hard surfaces. It looks from your pic that there is considerable
rust pitting at the muzzle. That would have to be re-surfaced at minimum.
If you feel the need for a crown there are plenty of inexpensive tools available.
If the bore is too far gone to be a shooter, you would be better off not touching the gun. With a bad bore, but a good exterior, the gun has some collector value, which it won't have if you re-crown it.