Most generators have 3 mounting lugs - 2 inline for pivoting and 1 for belt tension with an adjustment arm.
Alternators only have 2 lugs, 1 for pivot and 1 for adjustment.
Googling for a Hercules K motor I found this and it's nothing like the above;
It appears to be gear driven or an enclosed belt.
I found a generator to 1 wire alternator conversion for Hercules KL motors
here and their
FB page
Might be an option to look at.
