Post the year, better yet the model &serial number of the motor in modifications and ask is it possible to increase the 85 to a 140.
Normally it involves changing reeds and carbs, possibly spark stuff also.
Not sure how cost effective it may be, just depends on what good used ones you find.
Look in "Links" at "Fabrication, t-tops,
Aw hell, just go here and look at some possibilities.
I like the radar arch with bimini attached.
http://www.boykinmarine.com/