Yes, the old "bo-mar" rear sight fits the series 70 factory rear dove-tail perfectly. Contact the folks @ novaks sights, in parkersberg, w.va. And they can solve any sight install questions you have need to ask. They also do super-nice installs on both fixed & adjustable sights to the 1911 slide.
Keep in mind that some of the adjustable rear sights that sit on top of the slide will require a taller front sight.
If you really want or need an adjustable rear sight it might be best to have one milled into the slide.
Best Regards
Bob Hunter www.huntercustoms.com
Lots of 'em. Been kicking myself for 30 years for putting a fixed Millet on. Should have spent the wee bit more for adjustables. The trick is installing 'em. Like Hunter Customs says, they usually need a different front sight too. Buy a matched set. Front sights aren't a DIY thing though. Unless you have the tools and the skill to install 'em. Mind you, some of 'em are silver soldered on. Some are dovetailed.
I dont know if they still make em or not, but there used to
be a company call MMC that made a real small adjustable
rear sight for Colt 1911's that would go right into the stock
dove tail. It also worked well with the stock front sight. You
might look on internet and see if they are still in business.
I have used them in several of 1911's and they work great!