Below are the details on the sight cuts used on STI Pistols.

Front Sights: STI uses the STI/Heinie dovetail –  60° x .300″ width

Rear Sights: Rear sight varies based on model but would be LPA, BOMAR or NOVAK.

Image Source : http://stores.kensight.com/common-1911-sight-dovetails

LPA vs BOMAR

Image Source – https://www.egwguns.com