Your deck doesn't have any good sac outlets other than
bloodflow connoisseur. They all cost mana (and worse, 2 or more mana), making all the takeover plays very late.
What about cards like
Carrion Feeder,
Viscera Seer, Bloodthrone Vampires or
Nantuko Husk in creatures, or
Phyrexian Altar or
Ashnod's Altar in artifacts (that might also add to your tempo)? Or there is
Defiant Salvager, whose drawback compared to bloodflow is moot, since all takeover cards are sorceries anyway, but starts with one more power and toughness, or falkenreath torturer who is a strictly better version of bloodflow.
There are a bunch of other less-often-used creatures too if you prefer something more hipster, like
Blighted Shaman, or
Brine Shaman, or in artifacts
Altar of Dementia. If one wanted to get more expensive ($, not mana),
Phyrexian tower or
Diamond Valley. If one wanted to go weirder/less used
Burnt Offering, Sacrifice,
Culling the Weak,
Cabal Therapy, Dredge,
Accursed Centaur,
Kjeldoran Dead or
Bone Splinters, would all at least be only 1 mana plays (which either add more mana, more cards, very competitive 1 drops, force opponent to discard, or kill opposing creatures).
Or there is always Birthing Pods, which, while costing 1 mana and 2 life, would put a permanent creature on your board afterwards.