Also, try the crawler forums for max based crawlers and gear reduction ideas:
http://www.rccrawler.com/forum/index.php
We do love custom vehicles and trying new things, but this is a 99% electric forum after all. A nice reduction box of some sort would be cool, as would truggy ratio diffs to lower the overall drive ratio- need some FLM hybrid bulks, UE ultralites, or the LST/Muggy diffs for that.