Being that you're new to scoped handguns I'd highly recommend you try a red dot sight first. My dad is 67, wears glasses, and has a real hard time using a scoped handgun (let alone iron sights), he has trouble finding the cross hairs in a fast snap-shooting situation. I put a 30 mm Millett Redot on his 5" 629 deer pistol and he loves it. One big plus is you can use a dot sight with both eyes open, makes it real easy to get on target fast. Compared to a magnified scope I don't think there is any accuracy disadvantage when it comes to shooting "minute-of-deer" out to 100 yds or so.
If you don't like the idea of a dot sight then I'd strongly suggest a Leupold 2x handgun scope. At $200 it's the Gold Standard by which all other handgun scopes are judged. I think you'd be very disappointed with a 4x scope on a big bore revolver except when shooting off sandbags and a very solid concrete bench. High magnification scopes are very hard to hold steady. But their biggest disadvantage IMO is narrow field-of-view which is extremely critical in a hunting arm, not so important in target pistol.
Scoping a Smith is pretty easy since they've been drilled and tapped from the factory for the last 12 years or so. Just remove the rear sight and attach a base. The only minus is you can't easily go back to the open sights. It is possible to drill & tap the barrel and mount a base forward of the rear sight (kinda like a Ruger Redhawk). That way you can remove the scope and go right to the iron sights. -- Kernel