I suspect your biggest problem (if it even is a problem) may be the physical difference in size of the two switches. Next minor pain may be the different flavours of electrical connector round the back, but again it may not be a problem.
Other than that it shouldnlt be too difficult. All they both do is connect two wires to stop the engine.
I converted a yamaha 15 kerosene 1978 model from a manual (the big button on the front engine casing at the side of the choke with 2 wires coming out of the back of it )
unscrewed the plastic retaining nut on the old manual switch which left it dangling on 2 wires ,
lucky the new kill switch was just about the size of the old hole ,tightened the new switch in place ,cut and joined up the 2 wires from the old switch leading from the engine to the 2 wires on the new switch and job done after making sure it worked a good few times .