I can see that the information provided is comprehensive, but I am having a problem following the parts needed for construction. It's probably cos I'm a girl!
And you will. I never intended it to be copied. No drawings or anything and no list of parts. And by it, I mean my many different chairs that all change or get updated over time. Because even I have no idea where I acquired most of the bits. I work in metal, whatever is on my bench, and do things differently as I go along. The BM3 chair is experimental, still a work in progress. Especially the control system. Trust me that's not plug and play!
Take a look here and see if you think you can do this:
http://www.wheelchairdriver.com/BM3-construction/MOST of it has little to do with the F55. And the parts that do are all modified. Even though it may not appear so initially. Of your donor chair, only the one bit frame (modified) and caster forks U shaped part (modified) is used. And the seat base and uprights, and rear light (all modified). All of the rest is not from an f55, much is ebay /other and mostly hand made. Whats more it will be way too lively for you as it is, you will need to change it a bit...
I might suggest that you aim a little lower to begin with like convert your chair to LiFePO4 for eg.