I can get some tonight. I'm not sure what area you are describing though. It is pretty easy as long as you don't mind a little gap at the back of the action. To move the action screw hole in the stock would be a lot more work imo. You will need a drill press with 7/8 bit for the gauge. 5/8 bit and a hand chisel to widen and square up the inletting and open up for the bolt at the front of the trigger assembly. Then notch for the safety.
I would really like to see your gun when you are finished. As you can see, I am a fan of the thumbhole stocks. My stock was on a Benjamin Titan originally. The hardest part and one I would suggest doing first is getting the trigger alignment to fit properly. Then you can measure for the gauge and screw holes. All you have to do then is remove any wood that is in the wrong place, fill any holes with wood filler that need it and viola, a thumbhole stock. Good luck.
Norm posted one with disco double way back...> https://www.gatewaytoairguns.org/GTA/index.php?topic=96216.0