IMO this is NOT a safe combination. NBOMe's are purely excitatory on the nervous system, and unlike all other psychedelics (except for the other N-benzyl PEA's), they have no mechanism that can attenuate the potentially dangerous vasoconstrictive and peripherally stimulant effects resulting from 5-HT2a agonism + catecholamine release/reuptake inhibition that occurs when NBOMe's are combined with a strong stimulant.
There is anecdotal evidence to support this proposed mechanism for negative interaction. Combinations of NBOMe's with strong stimulants have been reported to have the potential to cause severe muscle tension; in one post that I saw, the user reported physical discomfort and restriction to movement following concurrent administration of 25B and (high-dose) MDMA, as well as significant muscle pain in his/her back and neck that lasted for over 24 hours after dosing.
Furthermore, because 25C apparently seems to possess the strongest vasoconstrictive properties of the NBOMe series (except maybe for 25D IIRC), it is potentially even more dangerous to combine with strong stimulants than other NBOMe's.