Restoration of a Herring, Hall & Marvin Safe

Recently I purchased a HH&M safe on ebay; I only know that it is pre war HH&M because it has solid cast acorns. I have a couple of questions for you safe experts that if answered would help me considerablyl. First, I did not have a full set of hinge acorns so I had some acorns made of solid brass and my plan was to brass plate the handle and dial. But I do not like the look of these shiny brass acorns and was wondering if I can nickel or chrome plate these solid brass acorns (and of course do the same with the dial and handle). Second, I have been told that HH&M serial numbers are located on the handle. On my handle, I can see a four digit number (8192) and a two digit number on top of this number (50). I am wondering if my safe's serial number is 8192 or 508192. Lastly, I have read many posts on this fine forum about combinations and I am a bit confused by the function of the "last turn". The given (almost actual) combo of my safe is 91R-33L-60R- 7L.. Many times I read that the last turn (after 7L) would be to to the right where the dial stops. On my safe when I turn to the final number (7) I usually hear a distinct click and when I turn the dial to the right, the dial stops at about 0 and I open the door. However I can turn the handle and open the safe also when the dial is at number 7 and do not have to go to 0 . Sometimes I do not hear the click at the last given number (7) but the door will still open. However in this case, if I were to turn the dial to the right the dial will not stop at 0 and the door will not open at 0. The dialing is pretty smooth in general but the behavior of my lock does not seem to be consistent with my readings of your posts about the last turn. I am wondering if there is something wrong with my lock. It is a hand change Yale loick and soon I am going to (very carefully) take apart the wheels and degrease the components and wipe them down with a bit of Triflow. Based on the inconsistent last turn behavior of my lock, I am wondering if there is something else I should do while I have the lcok taken apart and have access to the rest of the components in the door. Thanks so much.