I'm assuming that your 1911 has the GI rear dovetail.
When you send/drive the gun/slide to a smith have both the front and rear done at the same time. For an iron sight comp gun you want a rear sight that presents a serrated flat to your eye with most likely a serrated fiber optic front. Look at most every gun used for this stuff and you'll notice that if they don't have a Bomar clone rear they have something that looks like one from the shooter's perspective. Send the gun to someone familiar with guns built for what you want to do with it and let them provide the sights and do the mill work. This is also the time you should decide if you want the slide flat topped. Bomar or Novak rear sight cuts are very popular and a ton of sights are made to fill them. You will easily be able to find a rear sight you like that fits one or the other.
You will be much happier with that gun as the years pass if you go ahead and get a nice set of sights installed. As most people spend time shooting they realize that they will be happier with quality guns done the way they want them than a bunch of guns that seemed neat at the time but just didn't hold their interest. Instead of getting that Kahr you're talk about I'd spend the money on this project if I were you.
