I've had a few #45's pass through the shop here, I believe the piston OD is 7/16" on these , kind of an odd size for A Jensen oscillating engine , I'll look in my parts bin, I know I have 1/2" oscillator parts.
That would be so helpful. I am working on getting a photograph. Wouldn't it be great if I can find one somewhere. Hope more folks are following our dialog. I am most grateful for you interest, help, and hope!. Bart1353