worn out 150's

I just purchased a 78 23cc that has a pair of x-flow 150 johnson's that have are still running but worn out, won't idle etc, not worth overhauling. The boat runs pretty good with the worn out 150's 40mph at 4200 rpm, any way due to my limited budget a new motor is out of the question, but I have found a pair of '96 90hp johnson's that have very low hours and are affordable just not shur how the boat will perform with this config. wondering if any one has any experience with a pair of small 4cyl john/evinrude's on the 23 cc ?