Transfer post from a site thta was infected

It is hard to say it considering that SoakSoak was the source of multiple attacks [1], some people may include spam in the published posts and even the revisions (also know as draft posts). Assuming that SiteCheck scanned all ninety pages and (as you already said) did not report any suspicious code then I would proceed to migrate those specific posts to the new database but without their revisions.

If it was me I would migrate these ninety entries to a temporary database and review at least five of them to see if their content is correct considering that some people hide HTML containers that includes spam in the body of the posts.

As I understand you will only transfer the data from the posts table which is good, but if I misunderstood your original message then I recommend you to take a look to this article [2] specially the third point that explains a basic way to find malware in the options table.

I also recommend you to read this other article [3] you will find a list of tools that you can consider to use to clean your site and prevent future attacks.

Let me know if you need more information.

[1] https://www.elegantthemes.com/blog/tips-tricks/how-to-scan-your-wordpress-website-for-hidden-malware
[2] https://blog.sucuri.net/2010/07/understanding-and-cleaning-the-pharma-hack-on-wordpress.html
[3] https://www.elegantthemes.com/blog/tips-tricks/how-to-scan-your-wordpress-website-for-hidden-malware

Thanks much Yorman!
I will let you know how it goes.
Adrian