I have not seen an SP suffix on a Day-Date case (only A, B, & BIC, as best I recall). Post some pics of the engraving?
Likewise, post some clear, sharp pics of the dial and the experts here can tell you if it is correct. Unfortunately, there is likely no way to know whether the dial is original to that specific watch. (Occasionally the warranty certificate will show the original dial code, but not often.)
All 18238 wood dials are burlwood, from one of several species (walnut, birch, African mahogany, madrone)
You might also want to have a look at these two threads -
https://www.rolexforums.com/showthread.php?t=750843
https://www.rolexforums.com/showthread.php?t=750086