Very nice image Greg
Always difficult to do these sort of panoramas when the Milky Way band is nearly overhead. Leads to a lot of distortion at the top if not enough sky is captured above the band. Much easier to do this sort of thing when the Milky Way is lower down, setting in the west or rising in the east. You could try stitching it in a more circular projection with the band straight and the horizon curved and then use the warp tool in PS to straighten the horizon. It can work well and can give more height to the frame without distortion in the plane of the Milky Way.
Cheers
Greg