I understand your point on (A), but don't see it as feasible.
If SWA were ordering another narrowbody type, then a case could be made for having one rate. But the 787 is a widebody and I doubt they would order more than a handful, at least to begin with. So let's say GK comes to SWAPA and says they want to order 25. SWA currently has 573 narrowbodies (per data on APC) on property. Is GK going to agree to up the rate on 573 737's just to get a lower than normal rate on 25 787's?
A better plan would be to have the 787 in a category by itself with pay rates that match or exceed the highest of the other legacies (SWA is now a Legacy for all intents and purposes). The training events would be minimal due to the # of widebodies in the fleet. The pilots flying those aircraft would get pay commensurate with the additional revenue generated by having a higher number of seats. International override would be on top of that.
As for (B), I'm in 100% agreement.