Can I set the preferred domain to get around differing content on www vs no-www?

Question

I am in the real estate industry and I am forced to serve content from servers at another host. I point to the content using a www. Subdomain referenced with a CNAME. Unfortunately, 15 years worth of links are pointing to pages on my non-www root domain that I host myself and I am not allowed to mirror my non-www pages on the servers hosting the www. Subdomain content.

i.e. example.com/links.html will not be found at www.example.com/links.html

If I tell Google that I prefer www.example.com will they expect to find the content mirrored there using the exact path?

I cannot replicate the exact path of my current non-www pages, but I can replicate them using a different path.

i.e. example.com can be replicated as www.example.com/custom-pages/index/ If I were to use a 301 to point example.com to www.example.com/custom-pages/index/

Would the new page still have all (or most of) the link power that domain.com/index.html had or would google not view a page in a subdirectory with as much favor as it shows my current root index page?

I am in a quandary because I effectively have two sites. All link power goes to the unimportant root domain and there are little to no external links to the www. Subdomain where all the content is. I’m looking for a solution as changing 15 years worth of links is impractical if not impossible.

Answer 1

I'm still not sure whether I have understood your problem correctly. Well, here's the crux of what I have been able to understand.

You have a domain - example.com which has canonical issues i.e. it can be accessed using both wwww and non-www versions. Now, both versions have different content and the link power is with the non-preferred version of the domain which has unimportant content.

Wow, that's complicated. How did you manage to do that?

What if I tell you to backup your unimportant content and move it to old.example.com and then using the .htaccess code redirect the non-preffered version of domain to the preferred one? TBH, I prefer to see the website first.website.