mike,
i put a maxxum 65 on my lx700 and used the nuts and bolts which came with the motor. make sure you REMOVE the old motorguide T-nuts or whatever they are called. If yours had an old motorguide, like mine, the old rubber inserts are a lot larger that the 1/4" bolt for the mk. I ended up reusing 2 holes and drilling 4 new ones. The fender washers are a must and go ahead and get some xtra nylock nuts and double nut them to be xtra sure they don't loosin up. If it is your fiberglass on the boat that is giving, you will want add some bracing underneath such as a piece of aluminum or steel which is as large or larger than the mk bracket. as far as the button on the foot pedel, mine was a little firmer but not much at all compared to my old mg. it took a couple outings to get used to the difference in location of the button but no big deal. this board helped me out a bunch with good suggestions on the installation and I'm sure others will chime in with some good ideas also.
jd