Make use of content from a penalized website?

Hi everyone, I have 2 websites in the same niche. One I got experimental with in terms of some black-hat practices, while the other I've done everything by the book.

The by-the-book website is starting to take off in this niche. Traffic has grown steadily, and each month it's breaking it's own records in terms of page views, rankings, and affiliate income.

The experimental/black-hat site is doing very poorly. I believe it got penalized somewhere along the way and I haven't been able to undo what happened to it.

Both sites have really great content. Original and unique, helpful to readers, step by step guides and information.

What I would like to do is make use of the great content on the penalized site and somehow transfer it over to the site that is doing well. I was thinking of re-writing each article and then doing a 301 from the penalized site to the other one. However I'm concerned that in doing so I might bring over some of the effects of penalization onto the site that's doing well.

Any other thoughts or strategies? Just nuke the penalized site altogether but still re-write the decent content on the other site?

Thanks for any suggestions!