Not that I know of.
No, there is not.
Best you can hope for is to find someone who can do the Valentine's Day missions for DJ Zero and tag along to get the Toga and sandals/laurel.
I've said it before, and its a matter of opinion, but the Valkyrie stuff with the mac-pack could pass for roman gear in a pinch. But its still not the roman gear.
Is there a way of getting to the Roman costume parts without completing the Imperious Task Force?
Thanks.