I wonder about pin bending reduced by wall thickness. In a 1.000" pin, .250" wall has only about 8% more bending resistance than .200" wall, but 17% more weight.

A larger OD is far more effective, but obviously there is only a small range that works. Going up from .927" (SBC pin) to .990" (BBC pin) with the same .200" wall is 27% stiffer. The .990" wall could be as thin as .125" with the same stiffness as the .927" by .200" pin (but much worse resistance to crushing and deformation).

The bending resistance is greatly affected by the unsupported span width. If the rod eye is 1.000" wide and the pin bosses are .500" away the span is .500" with the bosses 2.000" apart. Closing the boss distance to 1.500" (each boss is .250" thicker, but still has .250" float at either end) is a huge change. No, a spacer won't do this, the material must be continuous with the previous boss structure.

NACA duct as the compressor discharge port of an Eaton M supercharger: