What to Change? 15 y. old site with 6k backlinks same IP

This is a little bit "old school" of a topic so forgive my dated response. We can't check PageRank anymore, but back in the day (like 10 years ago) 6K quality links would usually make your website about PR3. So under ideal circumstances where the links are honest and true and don't need to pointed as part of a scheme you would be in a situation where you had advantage over other very small websites.

About 5-7 years ago PageRank stopped correlating strongly with ranking position. Instead the number of referring domains did. So not backlinks, but back-domains. This still seems to hold true. Number of referring sites correlates stronger than number of referring links. This change made sense because it is easy to get a site to give you 50,000 links just by adding your site to their footer. It is MUCH harder to get 50,000 sites to link to you.

About 3 years ago Google started testing schema ratings, CTR, bounce back to SERPs, social signals, etc and some of that appears to have stuck so backlinks aren't the only game in town anymore. They are still an important one but when accrued naturally they look more like "back-domains".

Here's the thing... Yes you can do the "old school" thing a point the blogs at your site and there will be a little bit of a boost but it wont be earth shattering or anything. you might outrank that PR1 in the slot ahead of you. OR ... you could think about this in a mode context. If you are creative you could invest a week or two in making 1 45 second video that is so f!@#ing fuy that everybody shares it and host it on the page you want to boost and work the keyword genuinely into the name in a clever way. If it is done well you get 10,000 backlinks, social share/likes/Idea, video views, text citations, real traffic,higher CTR, lower bounce back to SERP, etc. You see... the old school you are tweaking 1 band on a graphic equalizer. The new google wants to see multiple bands move. Moving one signal at a time is manipulation, but moving them all at once is a force of nature. (of course content marketing only works if you promote the content)

So in summary, yes it probably will work a little, no its not a great plan because the ROI is too low in my opinion and it wont be very repeatable, and finally there are better initiatives that you can do over and over again but they require you to think differently and be clever in different ways to pull them off.

I hope this helps you! And either way good luck and let us know how it works out.