I should have mentioned that the heart and arrow inlay is of silver.
Regarding the stag inlay, it does stand above the wood somewhat and at first I also thought that it might have been a later addition. The engraving is of identical style as the two animal vignettes on either side of the sideplate and although it is possible that the same engraver could have supplied it later on, I am thinking that it might have popped out and was glued back improperly. I have resisted the temptation to see if that is what happened and if I should "correct" it.
I have had this rifle for 35 years and have yet to really figure out all of the enigmatic things as discussed by you all. The A Z Brown rifle that I mentioned is the closest in appearance that I have seen to this one and that AZB rifle does have a similarity or two, but is still quite different and doesn't exhibit the quality of this rifle. I really hope to finally figure out one day who exactly made this rifle.