That doesn't seem too hot at all. A case that size could easily handle that many grains of 4350, IMR or Hodgdon. I am looking at the numbers for the 284 Winchester, 130 grain bullet, 54-58 grains for IMR 4350, and the 145 grain bullet is 52-56 grains of IMR 4350. 55 grains in the 6.5 with a 139 grain bullet should be close to max, but still slightly under.
These numbers came out of Speer #12.

EDIT---After looking at Hodgdon's website, that is pretty hot, so I would have to say that was IMR 4350, rather than H4350. Could you clarify on that please.