Bethowen good luck with the project!
A few suggestions that may help:
- if the mod is more towards making heroes 5 like heroes 3, check Waterfall mod Heroes 5 Armagedons blade, may be your ideas align so you can join forces. He is very strong on texture design where you will work on technical and balance changes.
- if the mod is more towards original heroes 5 and you are alright with the additions of MMH55 you can make a mod that stays true to heroes 5 classes and skill trees but balances everything else as per MMH5.5. This is the most requested mod topic and is a great niche for a mod!