I have a 20ga. 870 and it requires a firm cheekbone to stock to obtain a sight picture. It sucks.
I think dropping the comb would fix this problem for me.
I am not a wood guy. Woodworking is not my thing. Wood does make fitting an aftermarket buttpad simpler though.
 What is the solution?

I am thinking you have the standard type synthetic stock and have an issue with a bead sight barrel.   If this is correct then instead of lowering your face to the stock try raising the weapon in your shoulder to bring the weapon up to your line of sight.  This works of course with any sights.  Telling us the stock and sights you have could help guys give you an answer that may make changing stocks unnecessary.  I even had guy call me that was trying to shoot a bead sight barrel with a Monte Carlo stock since he bought the barrel to make his slug gun serve as an HD between hunting seasons.

Right you are and thanks.
Its a bead sight and syn. stock
My Benelli came with a set of spacers which can change the drop. This was simple and made a tremendous difference for me. Granted the Benelli has GR shights which are taller but  the shim did make a big difference.
 I like to mount the shotgun much like a rifle and shoot it like one. I do not shoot clays but rather more rifle like targets.
I would like to keep the 870 and thought a buttpad and drop change would make me happy.
If my technique must be changed, I may just stick with the auto. It is kinder on my cheek and fast on target.

Search youtube for Midway USA and I believe there is a video that may help you.  It's not that hard. if your worried about screwing up your butt stock you can purchase one from remington (remington store) in the closeout section for $14.


ETA: Didn't see that you had a plastic stock, Either way I believe they have the plastic stocks for $14 as well