I’ve been trying to find some diagrams for you, but haven’t had any luck. I did find this on eBay if you want to make the investment:
http://www.ebay.com/itm/Orig-Scott-Atwa … 1425601652
The 22HP was a one year motor — 1958. I have heard great things about the 22HP performance, and in addition to having good power like most Scotts/McCullochs during this time period,it supposedly gives OMC a run for its money when it comes to idle in this HP range. I’ve been searching for one for years with no luck. Anyway, you may have a gem on your hands, if it has been cared for throughout the years. I believe some of the parts are interchangeable with the more abundant 25HP, should you need stuff.
JP