Again, if 'should' does not go with 'have', then the sentence is grammatically incorrect. Seeing how there is no other instance of a grammatical error anywhere else in the entire Bible, I find it inconceivable that they would suddenly come up with one now.
Again, it does not say 'whosoever has'. It says 'whosoever have', meaning that there is a verb that goes with 'have' just as there is one that goes with 'perish'.