I disagree with Mystical Beast Serket. Anyways.
-2 Nisashi I don't think he's that good
+1 Cyber Dragon because he fits really well in these decks
-1 Double Summon, when I played it I found it to be really inconsistent
+1 Legendary Ebon Steed Helps your monsters survive, so even if they get destroyed by card effects they stay 1 turn more than normal
-1 Axe of Despair
+1 Legendary Ebon Steed, I find it to be better than Axe of Despair in Six Samurai decks.
There's my suggestions, can't think of anything else for now. That trims the deck down to 45, as I never usually go over 45. That's just me.