Though if you're on GBA/SNES, by the time you beat Sandworm, the only thing you'll be needing to grind is equipment drops or steals.
I finished maingame on my Dragoon + Trizerk and defeated Shinryu both at level 44(forgot about level 2 Old and happened to get there at 44 but was too lazy to go back and grind to 47 at that point). Hermes Sandals Dragoon jumping with Dragon Lance and Berserkers(Coral Ring + either Ice or Aegis Shield) with Equip Lance for more Dragon Lances.
I only had 3 Dragon Lances though, not the full 4 like I wanted. Only had 1 Bone Mail too because I couldn't get the rare steal on Thief Knife for it. And 3 Ice Shields at the time of Shinryu, but that one was thankfully just a rare drop. Took me some time to rare steal 2 Aegis Shields to bring me to 4 after counting the ones you pick up in chests.
Equip Lances and Equip Axes are the only useful skills to transfer between those 2 classes.
With those Dragon Lances, I was able to prevent Grand Cross from even happening. And the berserkers were nice about spreading the damage, so I didn't have to deal with an enraged final part.
I was considering saying screw Omega, but I'm going for it. I now have Bartz, Lenna, and Krile KO'd and am solo grinding Faris(her balanced agility/strength stat made me choose her, but maybe not the best choice, but too late now). Faris is currently level 76, which is still not enough. I need to check what the final multiplier before level 99 is because I don't want to get to 99 unless it gets me a multiplier.