outboard height on my 18

[Beaver]

Sorry if this has been covered a million times. I tried using search funtion and couldn't find anything.

I have an 18 CC with a 90 hp Tohatsu (3 cylinder so its pretty light). I think the motor may be too low since the cavitation plate is about 1" lower than the keel. My thought was to raise it at least an inch but maybe two. It seemed like I read where one guy had his set 1 1/2" above and liked it. Any ideas as to what it a good height for the 18? Thanks.