Exporting users, posts, threads, and attachments

[338Lapua]

I'm wanting to go from 4.2.2 back down to 3.8.7 because of a certain custom style/theme that was used on the 3.8.7 version.

Is there a simple way to modify the 3.8.7 style/theme to work on 4.2.2 or will it be easier to export the users, posts, threads, and attachments from 4.2.2 and import them into the 3.8.7 vbulletin version?

Thanks for your help!