About the Mercury outboard, if it runs you have a find.
My dad had one of these Big 10 outboards whenI was a child in the late 50's, talking about it later when I was older he said you had to face the boat away from the dock before cranking it as it didn'thave a shifter. Very heavy by todays standards but was always a powerful outboard.
The age seems about right, because my dad had a new motor back in '59 when I recall seeing one like this. By 1960 Mercury outboards such as the 60 (6hp) had twist grip throttle, thru hub exhaust, fnr gear shift,shallow water tilt/lock and were great motors. My dad bought one of these white 60's back in 1961 and we traded for a new 9.8 in 1975. Wish we had kept it.