Domain Confusion

I have two domains and have confusion which one to use for a long-term money site.

1st one is an expired domain with verified PR2, 2k non-spammy link (mostly PR1 to PR6 and from 70+ domains) and 13 yrs old domain... domain name is like a brand and also it is not related to my niche.
2nd Domain is a brand new domain but it is like "best-sheep.com" and say "best sheep" is my kwd.

I added the content on 1st one and also get visitors but not related to "sheep" .

So, the que is: is it fine if I move the content from 1st site to 2nd site and do a 301 from 1st site to 2nd one OR should I keep the existing domain. Please suggest.

301 is not a choice if you are going to handle the site in a long-term project. To host all your content at best-sheep.com is a better choice.

If you can rebrand the aged domain, build your money site on it. It's one of the ways you can fast track the process of making money from websites. I read about this technique in an IM guide known as BTF (Bring The Fresh).