Personally, I'd get it drilled and tapped.
ordered a Ruger factory mount
for my dad's Mark II and I'll probably do the same for my Mark II. I like them and they're made for the Marks. They come with the screws, too. Most gunsmiths will charge around $15-20.00 a hole for D&Ting. This particular one would look great on your
Plus, it has the Ruger logo.
I like it specifically because it sits really close to the top of the gun and doesn't unnessesarily float higher than it has to.
Btw, the Mark II that I just traded for had one of those clamp mounts (pictured above in your post) on it and when it was eventually removed it really marked up the finish of the top half. If you D&T, you can always get the little flush mount screws that thread in and disappear from notice if you decide to remove the mount.
After you get the red-dot installed, you should get the Volquartsen trigger and sear.
You won't believe the difference.