I really don't know for sure about the rear sight but when I was looking at replacing the sights on mine I read that the sights are pretty much cut to colts 70 series specs so anything you find for a 70's series colt sight wise should work. That being said I'm not completely positive on that I will have to look up my question on another 1911 forum to find the answers I was given.
ok upon further reading the rear sight is dovetailed just as any modern colt 1911 is so it should be very easy to fit the rear sight. the front sight I'm not so sure you would probably need to ask a gunsmith if they can properly fit it for you.
Here is one I found
Trijicon | Colt Gov't 3 Dot Bright & Tough Night | CA02
PISTOLS — Use CA01 or CA26 for 1911 pistols made after 1988; CA02 for pistols made before 1988. CA01 and CA02 fit the Combat
Elite & Delta Elite. These sights will also fit most 1911s made by other manufacturers. Call for details.
Note: Replacement of Government Model, Combat Elite, Delta Elite, Officers ACP and Combat Commander fixed sights require use
of Trijicon staking tool by professional gunsmith. Use of other staking tools will destroy the sights.
heres the site I the got it from
my understanding is the CA02 sights for the colt would work for the RIA GI same one I have. good luck and hope this helps. By the way if you do get them and have them installed let me know the details and a pic or two as I still have not yet replaced my sights due to lack of funds.