For a canoe that large – 56” beam, 47” waterline beam, bow height 34", stern height 22.5 inches, 250 pounds, if I've got the spec right – I would want a paddle longer than usual. A wide blade (8” or more) would help in close-quarter maneuvering, but you might want something a bit narrower for a long haul. A common way to determine paddle shaft length is to sit in a chair, and measure from the seat to your nose. For this canoe, I would add at least 8 inches to that. Total length is that plus the blade length.
Presumably you want the paddle for when your engine conks out – you might consider carrying 2 paddles, because this boat would be a beast to paddle solo for any distance.