Domain that will probably lose its power soon

Have a domain which has some decent juice flowing through it right now, but only from 2 domains (it was a throw-in from a broker with some other domains I bought).

I don't anticipate it lasting very long before the links are gone so I don't think it will be worth building out a PBN on, so I was thinking of just using it as a 301.

My question is whether it would be best to 301 to my money site (of which I'm trying to rank 1 inner page at the moment, not the homepage) or to one of my existing PBNs so I can control the anchor text.

Is a 301 at the registrar fine or would it be better to get a host and do it on the host level?

First I would be interested in knowing why you don't think these links will last? What sort of pages are they on? How long has the domain been expired (or dropped if it never actually expired)?

By 301ing, you are essentially giving your money site new links, but if you think that these will soon disappear then it will contribute to the link decay of your site. By this I mean that search engines might look at the rate at which a site loses backlinks as a negative sign and by 301ing the domain, you are essentially going to contribute to this decay at some point in the near future.

If you were to 301 it to a PBN, on the other hand, the number of links going to your money site would not change and so link decay would not be an issue. The only thing that would change would be the power of the link from your PBN site.

As for 301ing at the registrar goes - most will only allow you to redirect the root and not any inner pages. So if the backlinks to this domain only point to the homepage then it is fine, if they point to inner pages, it is worth putting it on a host and 301ing that way to ensure all the juice gets passed.