Mike, did you see and maybe take pictures of the 273 wrist pin compared to the Egge setup?
I have searched my garage for my 273 pistons/rods in a box but they may be at my sons house.
When my son did the 78-318 build with light weight pistons and wrist pins we weighted all 8 of his new wrist pins and they weighted just a little more as 4 of the 273's. So just about 1/2 the mass at the top of the rod. All 8 of his pistons, Hypereutetic, were about the same weight as his factory 273 pistons. None of his 273 pistons weighted the same maybe 10gr high to low. All his new .040" over 318 pistons were about 2-5 grams but were equal when he was done. They took 4 pounds out of the crank when balancing it.