Welcome to the group. JA #s will be somewhere under the lip or on the bottom of the machine cast into the head. That # on the plate is the serial # which is useless on a Japanese machine because there's no records to look it up. Very few machines don't have some kind of marks.
As far as making a cam, you would need to have a right one to copy or it probably won't work. Cams can be a real crap shoot. There were tons of different cams, sometimes a manufacturer used more than one style over the years, and most cam boxes aren't marked for what machine they go to. The best thing is to find a pic of a machine like yours that has it's cams so you know what to look for. Not always possible. The only other way is to buy cam sets until you get one that works in your machine.
Cari