well, tapping the receiver for a side mount is DEFINITELY a gunsmith job (and I mean a reputable rifle-smith). If it's done incorrectly, the sights will never track right. Honestly, for the money, I'd say get a picatinny rail for the receiver, and use a top-mount sight for the rear. Phoenix, Warner, or similar (you want something that'll track true, every time)
for a front sight, if you can swing it, you can't beat a Stallings Machine 30mm "RightSight". I've got one on my prone rifle, and it's never left me wanting for more. If you want to go low(er) budget, any quality 22mm sight will work too, but I'd definitely suggest something with an adjustable aperture. You can call Wayne too (@ Stallings), and talk to him (he's a good guy). Tell him what you're planning on doing, what kind of rifle its going on, etc etc, and he'll get you set up with the proper sight.
the biggest "what if" for your build is gonna be what kind of stock are you going to use. you want something with an adjustable cheekpiece (to make sure head position is perfect with that rear sight), and preferably an adjustable buttplate, so you can better fit the rifle to a comfortable offhand position.