Shopify Empire Theme Migration

We are looking for an experienced Shopify developer to migrate our store from Empire theme v8.1.0 to a clean v13.0.0. We recently attempted the update through Shopify's built-in updater, but it was unable to auto-merge four files (empire.js, theme.liquid, and two product snippets), which broke our product pages — variant selection stopped updating the price, along with a ProductGallery console error. We have kept v8.1.0 published so the live store is unaffected, and the broken v13 version is sitting unpublished. Following Pixel Union's guidance, we do not want the old v8 code carried over directly. Instead, we need a fresh, clean v13.0.0 with only the necessary customizations reapplied — adapted or rewritten for the new theme structure where required, not copy-pasted. Since we are not certain of every change made over the years, the developer should compare our live 8.1.0 against a clean 8.1.0 to reliably identify all existing customizations before reapplying them. Known customizations include a custom FAQ structured-data block (FAQPage JSON-LD) and tracking/pixel code in theme.liquid, plus anything else the comparison surfaces. Existing theme settings and content should be carried over to the fresh copy. Before handoff, the migrated theme must be tested across product pages, variant pricing, cart, collection pages with the new faceted filtering, search, tracking scripts, structured data, and app functionality. All work should be done on an unpublished duplicate and delivered for our review — we will publish only once confirmed. The live theme must not be touched or published. German/multilingual translation work is out of scope; we will handle that separately. In your proposal, please include a fixed-price estimate (or hourly plus expected hours), an expected timeline, whether you anticipate any customization needing a full rewrite versus a straightforward reapply, and your specific experience with Empire / Pixel Union themes. We will provide collaborator access to the store and theme.