you need to ask the permission to the original mapmaker since he/she owns the graphics rights on the map according the current CC Map agreement
When you have his/her approval, just let me know in any sort of way and you can start to work on the map.
Just two things:
1. I suggest you to finish your curretn project before starting a new one
2. Revamps are a pain to do.
Let me know if you need to know anything else
Give every man your ear, but few thy voice. Take each man's censure, but reserve thy judgment.