Either of the previously mentioned options would work just fine. Personally, I prefer to have my receiver sights mounted in the traditional manner. IMO, they're less susceptible to accidental damage in the field. I also like the somewhat lower profile and that they more often than not will 'zero' with the stock front sight with plenty of adjustment left over. Most top-mounts will need a taller front sight. Not a big job, I know, and some brands do include the new front in the deal. But often that new front won't work with the hood, and I like the little bit of extra protection and definition it gives.
IMO, it's worth the extra money to have a 'smith D&T two holes if they aren't already there. YMMV; value is entirely subjective. Around here the usual cost is about $20/each. Not cheap, but you have to understand that it takes some time to lay out the location and set the drill press or mill up for the job, which includes making sure that the workpiece is square and level with the tool.
Those holes a quite small, usually either 6x48 or 8x48. The drills and taps are quite fragile and it requires no small amount of care and skill to avoid potentially nasty surprises. If you've ever tried to extract a broken drill or tap from something, you know what I mean. The tools aren't free either, and he has to buy his, too. Personally, I'd rather pay the $40 to someone with better tools and more experience than buy the drills and tap and face dealing with any of the possible problems.
