The inwales should help, yes.

Was going to mention, should have asked earlier, if it'll be a lake boat, might just want to add an external keel after it's covered, protects the skin and stiffens the existing keel.

If instead it'll be a river boat, used on moving waters, you'll probably want to install the inwales first and see if that fixes the problem and if not plane it flat, that keel should be strong enough. An external keel doesn't help on moving water.

Bill H.