vBulletin 4 to 5.7 Upgrade

I'm looking for an experienced vBulletin developer to upgrade my forum from vBulletin 4.x to vBulletin 5.7.x.

Requirements:
- Upgrade vBulletin 4.x to 5.7.x
- Ensure all functionalities work post-upgrade
- Backup existing forum data before upgrade
- No custom modifications or plugins to consider

Ideal Skills and Experience:
- Proven experience with vBulletin upgrades
- Strong understanding of vBulletin 4.x and 5.7.x
- Ability to troubleshoot and resolve potential issues during the upgrade
- Excellent communication skills for project updates

Please provide a brief overview of your experience and estimated time for completion.