As stated, the bridge appears to be mid-60s chrome plated, while the tuners look to me more like the earlier nickel coated version. The knobs look to be the later 60s style. The inlay position (not central) indicates early 64 or earlier. The neck joint, where it joins the body, is the original style, used up until the end of '65. It should have holes for a metal string cover midway between the pickup and the bridge, as well as a thumbrest, which were included until at least 1969 (in 68 the cover moved to cover the bridge). So most of this dates it to a pre-65 bass, with possibly replaced knobs and bridge. However, the major thing is the Pickup. That is most definitely a 70s pickup. Starting in 69 they added the ring around them, as well as the Gibson name on the cover. You can see the pickup ring and pick guard don't quite match, and the earlier 60s pickups had larger covers. So, overall, to me it looks to be a pre-65 bass, with previously mentioned replaced parts, and a 70s Gibson pickup.
Regarding the color, I'm not so sure it's a refin. I've seen other examples of the older EBs in cherry that fade to a similar brown. Example