Brackets are vehicle specific, there unfortunately isn't a way to make a universal one. For a 1974 International Scout II we recommend a 204 installation kit for driver side or 204RH for passenger side. The mounted spotlight should have a "GM" length shaft.
http://www.unityusa.com/204-Installation-Kit_p_2241.html
http://www.unityusa.com/204RH-Installation-Kit_p_2242.html
http://www.unityusa.com/GM-Shaft_c_1579.html