I haven't used Universal in shotshells but I do know that pressure levels are lower with shot than with bullets. You might want to contact Speer and get their advice.
Lyman's load data lists this for a 255 gr lead bullet: 6.0 grains of 700X for 785 fps and 8.0 grains for 1,039 fps (maximum load) in Rugers and T/C's only. I have not tried it, just quoting the Lyman book. Those numbers are from a 10" T/C barrel.