Well, I've found something new that I believe is optimal for 5B "fullscreen" (really just means when you're not in range for 6C 214A):
[DM: 3160] +40 Heat
5B > 5C > Sekkajin > 66 2C > j2C* > j5C > jD** > 66 5C (before opponent touches ground) > 2C > sj5C > jc > j2C > j214B
*Delay for small characters
**Don't think this works on Carl.
-9 heat isn't worth 6 more damage, so for 3C > 214C capable characters just stick to the original combo.
When's CP...
[DM: 3275]
5B > 5C > Sekkajin > 66 2C > j2C > j5C > j2C > j5C > jD > 66 5C > j5C > j2C > j2C > j5C > (can't finish this with anything I can find)