g-day mate.... welcome to the club... i also planed on making an edge buggie and that's the precise reason im building one !!!! do you have an alias on the edge forum? um sounds like you have the right idea... im looking to make the same thing... try TEA transmissions they have an aussie office for R&P or ebay... i like your design it looks like you got the KISS concept prity down packed. you would be looking for 0.5-0.25mm accuracy?
hope it goes well mate i will keep a close eye on this one