If you are looking to give 3 Gun a try and it’s the shotgun you have on hand, it’ll work. In fact pretty well any shotgun would work for that purpose. But if you’re asking if it’s recommended as a ‘good’ competition shotgun, unless it’s been 3 gun / IPSC competition customized, likely it would not be most people’s choice for a ‘good’ 3G SG.
A good 3G Shotgun will have the loading port opened up for faster quad loading, an enlarged charging handle, oversize safety, add on’s like a match saver, tube extension, etc. Also many like to use a 3.5” chambered shotgun to allow more 2 3/4” shell capacity...although that’s not a game changer in itself. Also, most competition shotgunners don’t use pistol grips, they tend to prefer field shotguns.
Lots of good threads on this topic on CGN and YouTube for you to do your research.