WordPress: migrate off discontinued blog theme to a maintained theme + PHP Upgrade

Overview: I run thecastlerun.com, a WordPress blog/content site with regular traffic, hosted on Flywheel. My current theme is Oleander by Solo Pine but the developer shut down and the theme hasn't been updated in years, with no support available, which is also blocking me from updating PHP. (I'm stuck on 7.4 and need to get to 8.2.) I want to move to a current, actively maintained theme without my visitors noticing any material difference - same look, same layout, same functionality, and end up on PHP 8.2. My setup is very standard (standard posts and pages, homepage featured-posts layout, no page builder, etc.), so the content itself should transfer cleanly. The work is reproducing the design on a new theme and clearing what's blocking the PHP upgrade. THIS WORK IS URGENT - NEED IT DONE ASAP THIS WEEK. Current setup *Host: Flywheel (managed WordPress hosting, has a built-in staging environment with independent PHP control) *Current theme: Oleander by Solo Pine (discontinued, unmaintained, no support) *Page builder: None, standard classic theme *Current PHP version: 7.4 → Target: 8.2 (Flywheel's current default) *New theme: Open to your recommendation; leaning toward Kadence or GeneratePress unless you suggest a better fit *Site type: Blog / content site with the usual templates (homepage, contact, blog index, single post, etc.) Scope of work *Audit the current theme and active plugins for PHP 8.2 compatibility and tell me exactly what's blocking the upgrade (theme code certainly, but any specific plugins as well?). *Recommend a current, actively maintained theme that reproduces my existing design. *Work on Flywheel staging, never on the live site. Use Flywheel's built-in staging, set it to PHP 8.2, do all the work there, and give me the staging URL to review before anything goes live. *Reproduce the current design and functionality so the live site looks and behaves the same to visitors: homepage layout, navigation, fonts, colors, spacing, sidebar/widgets, all page templates, and post styling. *Migrate and preserve all content, menus, widgets, and custom CSS (or rebuild equivalents where a 1:1 transfer isn't possible). *Preserve all URLs/permalinks and on-page SEO/metadata *Go live by pushing staging to production, with a backup taken first and a rollback plan, during a low-traffic window, with minimal downtime. *Important Note - Newsletter signup: the current theme has a built-in Mailchimp newsletter widget. I'm moving to Kit (formerly ConvertKit) — please set up a Kit signup form in its place, not a Mailchimp one. To apply, please include *Confirmation that you can get this done asap, deadline this Friday. *A short note on how you keep the design identical during a theme switch (this is the part I care most about). *Which maintained theme you'd use for this and why. *Confirmation you've worked on Flywheel (or a comparable managed host) before. *A fixed-price quote and timeline (feel free to ask for a quick look at the site first if you need it to quote accurately). *One or two examples of similar theme migrations you've done.