I just picked up a wn7a serial 923363. It shows to be a 56 or 57. The plugs were out of it so I was going to try and pick up a powerhead used but want to stay original. The cross reference shows same as a Mark 25 but I thought some Wizards had different reed valve set ups and were less horsepower than Mercuries.The mid section looks like a mid section off a kh7 or Mark 20.Has anyone gotten into this before? Thanks