Rear Brake Problems

[Cheyenne Supr]

Hi all,
I have never had so much trouble with a set of rear brakes. I have a 69 C-10 with 6 lug wheels. I had a bad wheel cylinder on the driver's side so I replaced it and went ahead and changed the brakes and any worn springs as well. Although everything went together, and we have verified the parts are correct, the shoes just don't fit quite right when assembly was complete. There is about a 3/8" gap between the top of each shoe and the top center pin on the backplate (see pic with top springs off). Which makes the drum tight and the shoes are not against the backplate correctly (yes, the adjuster is adjusted all the way in). At first we thought the wheel cylinder links (push rods) that push the shoes out were too long, but I bought a new set at NAPA and they are correct (see pix). The rods are all the way into the cylinder. When I remove the rods from the wheel cylinder and assemble, everything fits together perfect. I'm considering grinding them shorter, but I'd really like to know what the problem is. I have a 3:73 rear end (HA code) with 6 lug wheels & coil springs. I'm wondering if maybe I need different wheel cylinders, but 60-73 seem to be the same. Perhaps I need C-20 cylinders? They are larger bore, but maybe shorter? This would mot be the first thing on this truck from a different year or model.
Any ideas?
Thanks for your help.
Larry