The bruising is almost certainly being caused by a low comb so the solution is to have it raised by a gunsmith.
The question is: ?By how much??
A really skilled gunsmith can get a pretty fair idea by watching you mount the gun in his shop, but if not, a trip to a shooting coach will have to be arranged.
You can of course do some experiments of your own: build up the comb with strips of rubber and tape to see if that alleviates the bruising.
What we?re looking for is a stance whereby you?re able to shoot with a fairly erect head, eyes level, and your master eye slightly above the rib?s centre when the gun?s mounted.
If this works, get an experienced fitter to confirm the measurements before having the stock raised by a professional.