Upgrade Vbulletin from 3.5 series to latest

We are planning to upgrade vbulletin from 3.4.x and 3.5.x series to latest version.
All our forums are vbseo powered.

We need to make sure that we do not make mistakes in following:
1. Change in title tags
2. Change in meta descriptions + meta keywords
3. Change in URIs
4. Not major changes in source code.
5. We are not using many addons but all our templates are heavily customized.

Kindly Suggest your opinion

There are too many templates changed from 3.4x and 3.5x to 3.8.0 series
But this will be good for your forum SEO
Maybe this will increasing your meta description and keywords