Great options johhny!In .224; .223RemAI, .22-250RemAI w/1-7" twist.
In .243; 6mmBR, 6mm Dasher, 6mm GT or .243WinAI w/1-8t for BR but 1-7.0-7.5"t for Dasher, GT & .243AI.
In .257; 25 Creedmore, 25 Souper (.25-08) w/1-8t if available.
In .264; 6.5X47 Lapua, 6.5 Creedmore, .260Rem or AI version w/1-8t.
In .277; Look into the Sherman lineup. Not sure what's available in short action and .473" case head.
In .284; Same as .277.
A fast twist barrel, at least 26", will allow you more bullet options, no matter the caliber. Figure on custom (a bit more expensive) dies for any of the AI's, which IMO, they would be worth it.