From your post above, it is not clear to me if your SPS comb is too high and you need to lower it ? Or, it is too low and you need to raise it ?
If it is too low, you could try something a stock pack as mentioned above. Or, install a Karsten's adjustable cheek piece (link below). The Karsten piece will allow you to infinitely raise/lower/adjust the cheek weld to a height that is comfortable for you. If you slant the adjustable cheek piece forward (ala Weatherby), it will cause the comb to drop away from your cheek during recoil instead of rising up and "slapping" your cheek.
If the comb is too high, as mentioned above, get a wood stock and gradually remove wood from the comb until it is comfortable for you. Another advantage to the wood and laminate stocks is that most folks can sand/grind/file to their heart's content until they come up with a shape that is to their liking...
Regardless of what route you take, good luck with your project.
Karsten Adjustable Cheekrest