I believe all front sprockets interchange between models, the chin.
Earlier sprockets used two bolt-holes to fasten the sprocket, I think, while later models use only splines and a fold-over washer to hold shaft nut torque. Sprockets are compatible regardless, model-to-model, I think.
The critical dimensions reside in the splines, I'd think--all common, as far as I know.
The offset may bear watching, the distance the sprocket teeth are outboard of the engine, depending upon the orientation of the sprocket--which side is inboard, and which one outboard. Inspection of the old sprocket should guide you there.
Procuring another 15-tooth sprocket, or . . . ?
From the tentative tone of this post, obviously, I'm not sure! Corrections and clarifications welcomed.