I dont follow the fina/deca gyno stuff much because neither one EVER gave me symptoms like test did, even running 700 fina weekly, where 600+ test gives me mild stimulation.
With that in mind, the B-6 would be used for fina/deca stuff and I do not know if it works at all for testosterone aka aromitzation gyno. Dostinex or bromocriptine (cheaper but has some sides reportedly) would be used for this fina/deca type gyno, in terms of actual meds. Since B-6 is readily available though, go for it.
Along with that 700 fina I ran 200 drol ED, no issues at all, only from test. Currently I run letrozol with all cycles, previously it was arimidex.