Interesting question.  I measured ten rifles and came up with slightly varying measurements, but from what I found, you can safely say that a drop from the bore centerline of one inch at the nose of the comb and two inches at the heel would apply to many high and low walls.    I laid each rifle on its side with the action open and placed a 3/16" cleaning rod in the bore, then measured perpendicular to the cleaning rod at the nose of the comb and the forward curve of the butt plate to arrive at the following:  HW=high wall, LW=low wall, SS=special sporting, PS=plain sporting, TD=take down, SB=shotgun butt.

Rifle             Drop at Nose         Drop at Heel

 LWSS                              1                                     2
 HWSS                             1                                    1 7/8
 HWPS                              1                                     2
 HWSS                              1                                   2 1/8
 LWSSTD                          7/8                                 1 7/8
 LWPS                              1 1/8                               2 1/8
 LWSSSB                           1                                    1 3/4
 LWPS                              1 1/8                                 2
 LWSS                               1                                      2
 LWSS                               1                                      2

I suppose if you wanted to really get sticky about it, you could add 3/32 to each measurement to account for the thickness of the cleaning rod.  It appears to me that some of the differences could be accounted for by variances in the manner in which each action was inletted, and by specific drop dimensions being ordered by the customer.  Hope this helps.

Thanks Dennis.  That is exactly the information I was looking for.
Phil