ORIGINAL: Missileman
IF it was my plane.
I would glass the current cutouts, repaint the cowl and put whatever engine I want.
From the pics the opening IMO look like a hatchet job anyway.
A 52 size 4 stroke would probably fit the best with the holes you have now.
Missleman, thank you for your thought... How do you glass the current cutout. I agree with you that the cutout is at best, horrible. Whatis a 52 size 4 stroke comparative too? I don't know anything about the 4 strokes.