Klondike,
If you're making a small, sinking, jointed wood bait, there are some things you might want to consider before you chose balsa.
You will need to add enough ballast to overcome balsa's most outstanding feature, it's buoyancy.
That may require so much ballast to be a problem in such a small bait.
Balsa is not a very strong wood, and that is critical in a jointed bait with hinges.
I'd go with a heavier, stronger wood that doesn't require as much ballast to get it to sink, both for it's strength, and because you don't have a lot of room for ballast in a 2.5" bait.
If I use wood, I like pine for small baits, because it's easy to carve/shape and strong. It is buoyant enough to let you ballast the belly, which will help the bait swim true.
But, if pine is too buoyant, I would probably look for something even heavier, like poplar, because I still want some buoyancy, so the tail section still swims.
Woods that don't float are a nightmare to carve, because they are very hard and full of oil,(teak and malaysian hardwood come to mind) and they are very hard to tune so they swim.
Small jointed baits are a bear.
Good luck.