[chumbucket]

JJ, welcome. On the canvas, I would think that even if you could go to the original mfg, it's going to cost about the same as custom, IMO.
Also just my opinion, but I don't think I'd go through all the work involved in changing to a bracketed outboard with an original outboard motorwell design. If you really are determined to get that much more speed out of the boat, I might be inclined to try re-propping the motor and maybe even trying the jackplate to raise the motor a little.