It depends on what you’re looking for. If you want accuracy, use Flamethrower or Fire Punch, since all fire moves are special in Gen 3. If you would prefer extra effects to accuracy, go with Blaze Kick. It has a 1/8 critical hit chance and a 10% chance to burn (though the burn chance is the same for Flamethrower and Fire Punch as well, so I’m mostly talking about the increased crit chance). Brick Break is a good move, and I see no use in replacing it besides if you want to use Sky Uppercut.
I would try a moveset of Brick Break, Flamethrower, Earthquake, and Return/Rock Tomb, personally. I think you should keep Brick Break since it’s STAB. Flamethrower is STAB, and even though it doesn’t have the increased crit chance, I would choose it over Blaze Kick for the accuracy. If you can’t teach it Flamethrower, I would recommend Fire Punch, unless you really want the increased chance of getting a crit.
Hope this helps! :)