Bob,
I don't have direct info, but I can give you a ratio from QuickLOAD. In QuickLOAD, I took the Speer 250 grain LSWC that is 0.66" long, and loaded it at the full 1.6" COL and put in enough Bullseye to give me the SAAMI MAP of 14,000 psi. I then assumed your wadcutter is 0.1" shorter, or 0.56" long. I seated that 0.020" over flush with the case mouth (1.286" COL), and found the charge of Bullseye that then reached SAAMI MAP was 20% lower than for the LSWC at 1.6" COL. This is due to the seating being deeper. So my first guess is 20% lower powder charges on the general assumptions the powder is quick.
Reality check: I went to Alliant's site, and their maximum Bullseye charge for the Speer 250 grain LSWC seated to 1.6" COL, same as I used in QuickLOAD, is 7.0 grains. QuickLOAD had given me 7.2 grains right at max and gives me near max 13,300 psi with 7.0 grains, and velocity at that charge weight agrees to within 14 fps with Alliant, so it was surprisingly close in this instance, despite the fact QuickLOAD doesn't always do well with straight wall cartridge cases. That gives me further confidence in the prediction. Unless your bullet lengths give you greater seating depths than I had (0.326" for the LSWC, and 0.540" for the imaginary wadcutter), I think a starting load of 4.9 grains of Bullseye, for about 750 fps from a 5.5" tube, and a maximum of 5.7 grains for about 850 fps is likely to be a ballpark range.
You can get comparable seating depths to the ones I gave using your own bullet length from the following:
Seating Depth = 1.266" + Actual Bullet Length - Actual COL
Check that against the numbers I gave. If it doesn't match, PM me with your actual bullet length and COL and I can rework it.