I did similar on a 92. I made up a 5/16" round brass extender about 7 inches long. One end in the drill and a 1/16 bit in the other end. This way I could drill from rear to front w/o needing a lot of angle. The paint filled dimple became my drill guide so the FO ended up in exactly the same place as the OE white dot. A 1/16 bit is .062" which works nicely w/ .060" FO tube.
I got to handle a full size that had been milled for a SRO by Primary Machine at a match this past weekend. It was impressive enough that I started searching for one when I got home. A lack of availability and needing to machine a $2000 gun are the only thing that stopped me buying one. I’ve been pretty happy with the Shadow 2 OR mounting system on my CO guns. I hope Dan Wesson releases the DWX with a similar system.