My son ask a question of his Savage O/U its a Model 24 .223/20 gage I believe its a 2 3/4 chamber. He ask if the gun could have screw in chokes installed and would it be practical. I know that some guns have collector value due to the cartridge arragement so I can't answer it, Hope some here might have approached this setup
He wants to set it up to as a backup gun for hunting turkeys. while hunting with his daughter.

Yup. Companies like Briley can put chokes into it. The addition of chokes will not make it steel compatible. The steel in the barrel is generally softer than the steel shot and the shot will leave scratches down the bores.

http://www.briley.com/

In addition to what speer said the muzzle has to have enough meat to it so the muzzle can be bored and threaded. The Briley system uses a form of shallow square threads so that helps out.

Send it to Briley.
Plenty of meat in the barrel for a screw choke.
Steel shot won't hurt it, the shot cup buffers the shot from touching the bore.
It won't hurt collector value at this point in time.

I would pattern it first though. I have a Savage 24 .22/20ga 3" Cylinder bore that throws perfect patterns out to 35 yds with good loads. Most turkey chokes I've tried are overhyped and overpriced. I've shot more than a few boxes of steel through it with no ill effects either.

Best truck gun ever!

I agree with Tree'em; pattern it first! My Rem 870 with the modified tube shoots beautiful, close patterns at 30 yds with #4 and #6 turkey loads and I've killed a number of turkeys with it.

The 20G chamber is bound to be 3" in any modern version. IIRC Savage were already providing the longer ones 40 years ago.