Any competent gunsmith can do it. You don't say where you are. Give some indication of your location and I'm sure that guys will come on here and give you some names.
Since you are in a place with few or any competent Gunsmiths, a Machine Shop with an experienced Machinist may be able to help you out. Instead of Drilling on a Slope I would prefer using a endmill with the Receiver set up properly and firmly clamped in the Milling Vice.
Cheers
Dennis knows of what he speaks. I've done a few and the last one couldn't be touched with even a carbide drill.... That rear hole can be a real problem drilling and tapping... it's right in the hard heat treated area of the action... and the base needs to set a bit high at the rear so the scope is pointing slightly downwards to the bore before drilling anything...
The machine shop with the experienced machinist also needs to have a federal firearms business license.... There may be some but I don't know of any.