The wider the beam, the more length you will need to clear the gunwales on your strokes.
And, as you know there are two general stroke patterns: one more vertical, the other with the paddle splayed out farther. That will often require a different length.
On my big Sportspal S-15 canoe, I use a 280 cm double-ended paddle, can also use it to stand and paddle.
Werner is great. Bending Branches has some nice paddles, too.