Question regarding 301 redirect for PBN sites

Hi

I recently found an expired domains with a lot of good backlinks coming to "blog.domain.com" and "blog.domain.com/post-title". Normally i redirect all 404 pages to home page of the PBN site, but in this case, will it be better to redirect all 404 pages to sub-domain instead of home page? The target is to transfer most link juice from whole website to one single page.

I just 2 domains like that. Most links going to a sud-domain. I'm planning on transfering all link juice to the subdomain for 2 reasons - 1: most links already point to it, 2: to mix things up for my PBN so not all my PBN links are on main domain homepage. Alternatively you could also use both - the subdomain and the main domain homepage...

You could redirect to the sub-domain or even main domain, depending upon how you would like to structure and manage the site from that point.