You can either put in spacers between the butt plate and stock or add a recoil pad. In an o/u or a high powered bolt like the guns you're after, no one will make fun of you for adding a recoil pad. And if it adds the necessary pull that you're after, who cares what anyone thinks. (if you add a recoil pad to a .22lr, I suggest you don't go out in public much
[8D] ).
My dad's uncles are all five between 6' 2" and 6' 10", but they're all kind of long armed (you're supposed to have a wingspan equal to your height), my uncle Ronnie is 6' 5" and has a 7' 3" wingspan...he shoots O/U's for clay games a lot, he just uses a recoil pad on most guns, but his clay game guns, he does the following...
Get an exacto knife and some leather from a saddle shop or hobby lobby, preferably 1/8" or so (8oz) veg tanned stuff...cut out several copies of oblonged coins the same shape as your butt plate. Paint the end of your buttstock's wood (under the butt plate). Figure out how many shims you need, then contact cement them together and oil them with furniture oil. Drill the butt plate holes trough them and mount them under the butt plate. You can dye them in an alternating light and dark pattern and it really makes a cool look. If you really want to get into it, you can cement them to the butt stock permenantly, sand your stock a bit, and put on a coat of hard laquer to really make it look neat.
It's a lot of work, but it turns out a LOT better looking than any shims I've seen, but if it's not your thing, a good recoil pad or aftermarket shims are a good, inexpensive way to go. You could also consider adding a target rifle butt stock extension, but it would be very expensive.