Will the 75 LMB be Fla strain or northern or F-1s (Fla X northern)?

If the 75 are Fla strain you will not be able to tell genetically the difference between them and CB because I don't think that can be measured yet. Fla , northern and F-1 or Fxs can be genetically determined (not cheap to do and only a few places can do so). Cross breeding in this context means crossing 2 distinct species not 2 strains of LMB or 2 types of Fla LMB. For example if 2 humans have a baby it is not a cross as both parents are human (one species).