The short answer is yes, those steppers will handle 30VDC very well. They will only draw 1.2 amps so too many amps on the power supply doesn't hurt. It just costs more.
Like Al said, your question has been answered many times on this forum. I don't remember the specifics, but you should be able to go 6x the rated voltage, in fact, its preferable to be at least 4X |