As I can't see a taper on the bottom of the crank for a blade plate hub ,it's possible it's an early Rotomo crank.(501 to 1246)
Number 1247 and on had the tapered crank end for the tapered sleeve (or blade plate hub)
No mention of the split pin hole in the paperwork so not sure if the factory drilled that or someone at home drilled the crank but if it was factory drilled you'd expect it to be a perfect centre hole.
Unless you find another original mower,outboard ,etc with the same crank it's difficult to say for sure what this crank was used for.
