Thanks to everyone for the input. Based on what I've read here and the info I found in my research it sounds like I'm OK rolling a safe across the floors upstairs as long as I stay under ~600 lbs. It's getting it up the steps that I'm sweating. I've got some trusty friends that can help me. If anyone has tips on how to get a 600 lb object up a flight of steps I would love to hear how you did it.
Thanks again.