I have 2 questions if anyone can help me out

I picked up a 50's keystone from a friend.
does anyone know where to find owners manuals for this motor I'm not familiar with the older style outboards and I would like to rebuild it closest to original as possible,

question #2
im new to buying parts online does anyone have a suggestion on where to get older parts for the keystone and an 80's mercury, I know the mercury isn't that old but small engine shops where I live charge you 5x the amount on eBay or anywhere else and usually always says it's no longer available from his dealer for parts