S'G' Datasheet - Front and Rear Sights

I’m down to the final details to finish up my Data Sheet and would like to ask for some assistance on the front and rear sights.  I believe the front sight key retention is NONE.  As for the staking, I was about to declare NONE, but if you look at the picture below there is a stake on the front of the key, internal of the sight's keyway.  What say ye?

As for the front sight pin staking, it’s either #1 or #4.  I think I see a concentric circle which makes it a #4.  What say ye on that one? 

Front sight shape is either a #1 RIDGE or #5 SLOPE ONLY.  There isn’t much of a ridge but there is a slight machine mark in the area of the “ridge”.  How do you vote on that one?

Now for the hard one.  The rear sight base has been pounded for some reason.  The leaf itself has been v-notched but the B-S'G' is clear. With a magnifying glass I can make out the S on the base left side.  On the right side you’ll see what at first looks like a P, but inspecting at different angles I can tell it had something on the bottom side.  Although it may just be indentations from the pounding it took, it looks more like an R followed what appears to be the upper left corner of a straight sided letter.   Can anyone tell if the letter placement relative to the pin hole would suggest what it might have been?  I wonder if it was changed out for the V notch leaf or removed for cutting the notch?  Any thoughts on the history of this sight and what do I call the sight pin staking for this one?  Leave it blank or make a note?