Well the combo you have started with is an ok load. You can actually go up a half grain(powder) with the Cheddite hull and the Federal wad. That hull is pretty spacious inside(for a 28 of course). The Cheddite primers are not too bad. They have the brisance approx like the Winchester 209. As far as the 410..7 1/2's will load but the patterns will be a bit thin. The winchester wads are for use in tapered (inside) hulls such as the Winchester and Rem STS.. Nobel and Cheddite are probably the same case for all intents and purposes. Luck with your shooting. Using the right chokes at the same ranges as the 12 the 28 will come pretty close to the same breaking percentages. The 410 ...will be a BIT different I think!
oh on the WW28 and WW 28 wad...a bit more wad pressure and 13 grs of Unique ot even 12 1/2 grs.