I'm at about 1.4 volts with the multiplier set to 23 sitting at 4.6 ghz hitting 55c. I'm wondering if I can go a little higher as long as I stay below 63c?
It will vary with every piece of silicone. As long as you stay below 1.5 volts on the vcore, and your thermal margin is in the double digits, you should be fine. Mine hums right along nicely sitting at 4.7GHz @ 1.4250V.
I usually rely on AOD's core thermal margin instead of core temps. But core temps are fine to go by if you know they are accurate. http://www.amd.com/en-us/innovations/software-technologies/technologies-gaming/over-drive