I don't think ghost quarter would work very well. In my meta, they use a ton of basics already.
I've noticed that I'm so used to not wanting to chalice @ 1 because of the welders. Now that I don't have welders anymore, the only thing it shuts of for me is sol ring.
I need to start chalice-ing for 1 more often.
Maybe find a way to fit steel hellkites back in.
My original question too though,
When sideboarding what do I take out in certain matches. It all seems good, so I have trouble picking what to take out for sb cards.
Chalice of the Void doesn't really interfere with Goblin Welder if you are running Cavern of Souls in your deck, which in my opinion is a necessity in a Welder deck in this day and age.
Here's a quick sideboard run through as to what you should cut:
Dredge: Smokestacks, Tangle Wires, Revokers, Dismembers, Chalice of the Void, Mana Crypt
Oath: Revokers, Dismembers, Some number of Lodestones, Some number of Moxen
Fish: Thorn of Amethyst, Mana Crypt, Sculpting Steel
Workshops: Trinisphere, Thorn of Amethyst, Mana Crypt
Send me a PM if you want more matchup and list specific SB help.