Im not too sure, but at 600 attack, my MS were somewhat underwhelming. Increasing my attack to 740 (with food - Bison Steak) and now my MS do 2.5k-4k on Nightmares, generally around the 3k mark.
I know this doesn't answer your question directly but the info maybe useful to you in your own att build :)
92-102 is a good enough estimate, it's reasonable to assume that DCs in Dynamis possibly have slightly lower stats than the mid tier VWNMs as, after accounting for other mechanics on those NMs, damage lines up well enough.