What to do when you buy a Website without it's content which has a few thousand pages indexed?

[MikeAir]

I am currently considering buying a Website because I would like to use the domain name to build my project on. Currently that domain is in use and that site has a few thousand pages indexed and around 30 Root domains linking to it (mostly to the home page). The topic of the site is not related to what I am planing to use it for.

If there is no other way, I can live with losing the link juice that the site is getting at the moment, however, I want to prevent Google from thinking that I am trying to use the power for another, non related topic and therefore run the risk of getting penalized. Are there any Google guidelines or best practices for such a case?

[BeanstalkIM]

I suppose that technically if you really wanted to come clean you could ask the currently linking domains to remove their links since the subject of the site has changed.  Those that don't, you could disavow.

I'm not saying to do that or not, and I don't know if I know anyone who would but it's an option.

[MikeAir]

I am not too sure about it. I've seen one project in the past where a site most likely was penalized after the same kind of scenario and it was much less pages that were indexed. The site didn't rank for over a year for it's own domain name.

Also I am not sure about the thousands of indexed pages, if I can just let them become 404 errors or if I should do some redirect. Or perhaps should I remove the pages from the index via WMT?

[Gijsbert]

I can't imagine Google would "think" like that and can't see any reason why they should penalize you. Same like moving to a new house; old furniture out; new furniture in.

You are lucky with the age of the domain and the root domains linking to you.

If possible, use http status codes correct http://moz.com/learn/seo/http-status-codes

[stever999]

As soon as you update the content Google will re-index and re-rank the site so you'll lose anything that was built up by the current content anyway.

If the linking domains are completely irrelevant to your new content they are likely to hold very little weight.

Finally, as the domain ownership is being transferred and the content completely changed you will almost certainly lose any domain authority that has been built up over the years.

Basically, I'm pretty sure that Google will treat this as a completely new site. You won't be punished for trying to use the current sites ranking but you won't benefit from it either!

Hope this helps.

Steve