The proper load should be on the table, or underneath on the barrels themselves.
: With GOEX BP, you may have to use 20 to 30gr. MORE powder to get the regulation velocity. Shooting apart seems to indiacate more powder is desired. 11 bore is more akin to 10 than to 12 for loads. The 2 loads I've found for 12 bores ran 150gr. for the light charge and 192gr. for the heavy. These may be paradox loads. My old Fluid Steel 12 bore smoothbore, shortened to 26" shot perfectly(as near as could tell) with the heavy load, but crossed at 100 yds with the light, easier to shoot load.
: With Swiss BP, you should be able to use the designed loads. Ross Seyfreid found Swiss to give approximately the same POI as regulation loads in double ans regulated tothe sights on singles.
: The loads listed came from on of Jack Lott's articles in Gun Digest having data for double rifles (or perhaps from "The Gun and It's Developement" WW Greener - 11th edition)
: 150gr. is 5.5 drams and 192 is 7 drams.
: How Lancaster's oval bores run loads, I don't know, but that class of rifle should give the loads. I'd expect a letter to H&H might result in the answers you require.