MTG Salvation

I do have one Immortal Servitude in the SB, but it usually doesn't resolve. I'm thinking about switching 2 Spectral Processionsfor two Lingering Souls and add two LS more to the sideboard, for the flashback cost I may stick a playset of Caves of Koilos, as having 4 swamps will hurt the mana base way more, and i'm not sure about using shocks here.

Has anyone have any recommendation for SB against UWR? I've added 2 Caverns to the main as the local meta has a good amount of control, and i'm thinking about removing the GQ, since it only hits celestial colonade in our meta, and having 5 lands producing colorless spells for Spectral Procession / Multiple sisters/ascendants/martyrs is not good at all.

Has anyone advanced with this? Added any updates? I haven't tried the builds yet, but I was planning to play a deck like this, gotta get the cards first though, I'm barely new to modern.