Aren't all the motors more-or-less the same? If not, post a photo.
Re engine numbers:
B18075, B19452, B19452 are 1925
B30170 is very late 1926
B32786 is 1927 so probably wedge tank?
Re the frames that don't fit the motors, BSA had 350s, 500s, and twins, with vertical and sloping motors, through the mid-late-1920s. That's assuming they are BSA and not something else entirely. Frame numbers will tell.
Cheers
Leon