Does your 115 have this boss and a screw hole under the balance wheel?
https://www.quiltingboard.com/member...38-582790.html
I do hand crank demos on my 99s, 66s 28s, etc and use an original and 3 aftermarket ( Chinse) HCs. The Chinese take a bit more lube and you gotta check for screws that try to slip, but overall they go a good job.