GRUMPY is 100% correct on the coils if you choose to go with newer style ones.

You also would have to swap out the EOS switches as WPC assemblies use low voltage switches that close when you flip, and older (Sys 11) machines have high voltage switches that open when you flip. High Speed also has lane-change switches on the lower EOS flipper switch stack that would need to be transplanted if you want to keep the engine revving sound when the ball is in the shooter lane. I don't believe think there's one on the upper flipper as there is really no need for it, but I cant recall.

The coil stops will also be different, positioning the flippers slightly different at the end of travel. They can be changed of course. For the upper flipper this won't be a concern.

It sounds like alot but it's pretty easy to use a WPC assembly in any game for the most part; The real question is why do you want a whole flipper assembly? You should be able to upgrade any worn parts easily without needing a whole flipper mech and the headache that comes with that.