i think i will either buy some 2 3/4 ammo or dig out my old SBE
A wise course of action. Get the correct ammo for the gun. Sporting guns are made for sporting loads
If you just gotta tote your trusty O/U clay-buster in the field, cheapest thing is to get 2.75" steel shells. You might have to look around a bit for them, but they're out there. Also make sure you use chokes that are rated for steel shot.
Personally, I think the SBE is the way to go. Now, taking your 525 to a dove shoot...good fun!