You have +0 MAB and +0 INT erroneously listed for Searing Cape and Othila Sash, but Maniacus Sash would beat out Othila Sash anyway, since Magic Accuracy doesn't matter for Meteor. Factoring in magical crits, Nares Cap also gives a 5% critical hit rate. Also, each Elemental Skill adds 1/6 INT. You put a bit much focus on MAB over INT, which I feel could be spent better. As a Hume BLM/SCH with no merits I have 95 INT and 424 Elemental Magic skill, so added up 165.67 INT and 40 MAB. Assuming 0 MDB mobs, that gives me a mRatio of 1.4.

With your listed gear I'd have an additional 106 MAB and 61 INT and 5% CR (critical hit rate), which would bring my total INT to 226.67, my total mRatio to 2.46 and my total CR to 5%, which means Meteor would deal 1949 damage.

Maniacus Sash has MAB+7 over Othila Sash's MAB+6 and an additional CR+10%, which would increase the Meteor damage to 1965.

Goetia Mantle instead of Searing Sash:
INT+8.17, MAB-5 => 1994

Icesoul Ring instead of Strendu Ring:
INT+7.00, MAB-4 => 2020

Icesoul Ring instead of Galdr Ring:
INT+1.00, MAB-1 => 2020 (no change, but infinitely easier to get than Galdr Ring)

Strophadic Earring instead of Hecate's Earring:
INT+3.67, MAB-2, CR-3% => 2033

Maleficus instead of Dorje:
INT+10.0, MAB-15, CR+10%, CD+30% => 2050

Ankylosis Wand and Avalon Shield instead of Maleficus and Wizzan Grip:
INT-3.00, MAB+15, CR-10%, CD-30% => 2091

Finally Laevateinn and Wizzan Grip instead of Ankylosis Wand and Avalon Shield:
INT-7.00, MAB+35 => 2335

(That's assuming no Aftermath.)

Those are the things I can think of right now.

As for combined casting, not only the last one matters, but also the order of the ones before. You should all go out and nuke a mob with your best set, and compare damage. The order of the casters should be the ascending order of the damage dealt, the lowest damage BLM first and the highest last. That way you will maximize your final damage output.