Ya might wanna try these depending on what components you have on hand. All are for the Winchester AA Compression Formed hull.
Win. 209 primer, 16.5 grains RD, One Win. WAA12SL wad with one 20 ga. BP .125" card under shot. 1181 fps at 7200 psi.
Win. 209 primer, 17.0 grains RD, One Rem. TGT-12 was, one 20 ga. BP .125" card under shot. 1196 fps at 7000 psi.
Win. 209A primer, 17.0 grains of RD, one Fed. 12SO was and one 20 ga. BP .125" card under shot. 1197 at 7900 psi.
Trouble with using RD with 7/8 oz. loads is most require the .125" card to take up space.
You might want to look at using 18.0 Clays with W209 primer and one Win. WAA12SL wad for 1245 fps and 8000 psi.
GB