Scratch that, went digging in the files and found the config file that let me change the window size. We're in business and will be fully switching over to Severed Chains for the rest of Legend of Dragoon.
Okay, so I've got Severed chains set up and everything transferred, but there's an annoying problem.
The window resolution resets to default every time I re-launch the game.
It's not a deal breaker (I have to manually set A Robot Named Fight too) but it's definitely a gripe.