I have a 1911 Target in .45 that I need a set of sights for. I ordered a set, unfortunately they are for a .22 which are of a different size. Sig doesn’t carry a rear sight, just front. I’m looking to upgrade to fiber optic. Anybody know what other make has the same size mount?

You might call these guys and make sure, but their website says the proper sight for the SIG 1911 .45 is a Novak dovetail.

https://dawsonprecision.com/gun-sights/sig-sauer/

Here's their Novak dovetail pattern page.
https://dawsonprecision.com/sights/novak-sights/