A lot of creative swaps are possible between and among the various Kiekhaefer
made outboards. It is possible to make a single cylinder KE4/Mark 7, WF4,WG4
as the bolt holes,exhaust openings, driveshaft splines and water tube line up so an earlier Kiekhaefer single cylinder powerhead can be mounted without alterations...I do not say they would work at all well...different gear ratio
likely would overwhelm single.
Adapting air cooled or other brand water cooled motors takes more work
and may require considerable alterations.
When you run into a more or less well done conversion you have to admire
the "where there is a will there is a way" attitude.