Kuldotha Forgemaster can take Combustible Gearhulk's slot- no one should ever let you draw 3 cards and you don't have enough recursion to make the mill side of that ability that threatening (I see Daretti, Sun Titan, Sharuum, and Scrap Mastery, but you run no tutors to get them outside of Tamiyo's Journal and only have a few draw spells so you may never see them together in a game).

Tezzeret the Seeker might be pretty advantageous here too as he can just grab the combo piece you're missing, ramp you, or provide a reasonable finisher. That's a lot of flexibility.

Thopter Foundry with no Sword of the Meek? Why? It plus Foundry and Ashnod's Altar/Krark-Clan Ironworks = infinite life and thopters.

Sword of the Meek could take Unwinding Clock's place- you don't run that many instants so untapping rocks is meh, and honestly the most it's doing in this deck is giving you pseudo-vigilance.

I'm really not big on Sharuum as one time recursion- he can win the game with Disciple of the Vault and Sculpting Steel or Phyrexian Metamorph, but that'd be another combo independent of your Commander. I think he's just a more expensive Beacon of Unrest in this deck as it stands.

PookandPie: Thanks for the suggestions. I plan to add Tezzeret, but I don't want to add in Sword of the Meek, as I'm not trying to make the deck into too much of a combo deck.