4 stroke weight on 1998 21?

[fish]

seacraft's newly updated web site states a maximum outboard weight of 550 lbs. for the 21. was thinking of repowering my 21, but all 4 strokes in the 200 and 225 hp range are heavier than 550. Has anyone done it? is the powerhead of the yamaha too wide to fit the transom notch. I called tracker hq and they don't seem to know too much about most things related to seacrafts.