Maybe you can try Experimental Synthesizer. Gives you some draw until end of turn, and you can sac it with whatever, and the effect triggers again. I also like Etched Champion quite a lot, as it is quite difficult to remove and is both amazing blocking and attacking. A substitute to Cranial Plating could be Nettlecyst, or you can even run both. Something like Skilled Animator, Kenku Artificer or Ensoul Artifact can also be very fun, especially if used on an Ornithopter or any indestructible land such as Silverbluff Bridge or Darksteel Citadel. Another affinity card I have a sweetspot for is Broodstar, but it needs colored mana, so it is not as easy to cast as a Myr Enforcer.

The deck looks very cool, love the idea. Maybe you can add some blinking effect, allowing to trigger again the first chapter of whatever saga you control, such as Flickerwisp and Teleportation Circle. Regarding sagas, I personally love The Modern Age  ^Flip, but I don't think it fits. Regardless, good luck with the deck, it is amazing.

You might like Fallen Shinobi in place of Dragonlord Silumgar. It is not a perfect substitution, but I think your deck can easily get some unblocked creatures and ninjutsu it, and the cards you steal can be cast without paying the manacost, so avoids any problem with colored mana. Agent of Treachery is also very cool, but might have the same problem with manacosts as Dragonlord Silumgar, but has the upside of having an effect that is repeated through the turns and also you keep the permanents even if Agent of Treachery leaves the battlefield.

Also, I see the idea behind preferring Bloodchief's Thirst, but instant speed removal can be very helpful, and even though Fatal Push cannot hit creatures as big as Bloodchief's Thirst can, the instant speed makes for it definitely. You can always run something like Infernal Grasp, but for 2 mana you will always have a downside.

The idea of the deck looks good, but it is torn between landfall and zombies, I would recommend going for either one, but maybe not both. For zombies I cannot help you, I barely play with them, but if you want, there is a fun combo using Putrid Goblin and Thran Vigil, then killing the goblin. This will make it come back without the -1/-1 counter from persist, so if you have a sac outlet, you have basically infinite etb effects (and any other bonus the sac outlet gets you). You could also use some Deadly Dispute, drawing you cards and getting the Gravecrawler on the graveyard.

For landfall, get some fetchlands. They double the number of triggers.

Also, you might need some interaction. I do not think Pick Your Poison is enough, and getting some instant speed removal might be nice

Maybe you can include Unctus, Grand Metatect so you can dig even deeper. Midnight Clock can also help both being a mana rock and letting you draw quite a lot of cards. I also saw you have Minn, Wily Illusionist, and I think it could be in the mainboard. It cheats a lot of things into play with the illusions, and with Shorikai, Genesis Engine you draw the cards needed to trigger the ability.

Mystic Remora is also a very good card that you can consider. Although you will eventually need to sacrifice it, the card advantage it gives you is insane. If you also go for the route of mass drawing, Ominous Seas can flood the board very quickly, but you may need to include some cards to have no max hand size.

Another planeswalker that fits VERY well is Teferi, Temporal Pilgrim, and the illusions it creates are amazing with all the card draw from Shorikai, Genesis Engine.

Btw, amazing deck, I still have to upload my Shorikai deck here, but it is much less flavorful, just centered around tapping and untapping Shorikai, so I love the much more dedicated vehicle theme, it is definitely a +1.