I like very much your build; I have been toying with this idea and gathering net ressources.

For now, alternatives to your deck I am considering are a singleton Torrent Elemental, Rattleclaw Mystic, Secret Plans, and possibly “Mahamoti Khan” Thousand Winds.

Having removal built in turning manifested creatures up seems great (Icefeather Aven, Kheru spellcatcher (counter and clone a Siege Rhino or a Tasigur?), or Aether Sprout with Thousand winds) as it adds versatility freeing single-purpose non-critter slots.

Some copies of Prophet of Kruphix might help despite being fragile and expensive, as they could grant mana to turn up nasty manifested creatures or flash big blockers face up or down…

I am aware my suggestions overload your mana curve though.

Some people to whom I talked have dismissed another natural idea, Ghostfire Blade, as Secret Plans seems more efficient for roughly the same cost.

Last, I think Reclamation Sage is a must for SB, especially if it can be bounced once or more with Temur Sabertooth…