Yes I was hoping the RX8 conversion blog would address some of the issues behind an ev conversion and how they were solved. Shame it petered out. Haven't come across any MX3 conversions so you are probably pioneering there but you may well pick up something useful from looking for a successful MX5 conversion blog.
What is your initial research coming up with for sourcing batteries and at what sort of price? With your aimed for range I would expect them to be a very big ticket item.