John, sounds like you're doing some good research, complimenting your first hand observation, then asking questions. Your approach for bringing the bike back to life sounds well thought out. Saying this, i am assuming your goal is to not only get the bike running and roadworthy, but also, at least for the time being, give it a thorough cleaning in the process. When these bikes have sat for so long without running, if the goal is to get the bike in operating condition, at least to my way of thinking, your approach is the only one. I've not studied closely your pics, but what i have seen, missing parts excluded, your bike certainly appears relatively unmolested from when it left the assembly line. That being said, once any nut or bolt is removed, the bike has then been "molested." I went through the same thing with 2157, it appeared obviously relatively unmolested, other than missing the engine, oil tank, airbox, side covers and exhaust ! If i wanted to ride it, i knew i would have to dismantle the chassis, clean, replace some parts and re-assemble, hence "molesting" the originality. If the goal is to make the bike roadworthy, to may wy of thinking, there's no other choice but to take things apart. Like your approach, i kept every serviceable part on the bike, for the sake of originality. Replacing missing parts is an individual decision. Obviously, replacing Lotus Roots anew is a "big" decision. Since my goal was to have 2157 a "rider," knowing i had no plan to restore the bike, not running Lotus Roots was the obvious choice. And, weenie i am, i cannot "wrap my head" around running a set of $3k+ exhaust and turning them into used parts that are going to rust out, at least not on a bike i would not ride regularly (such as my iron man hero Chris Rushton!) Restoration is another matter, and we have members who are very meticulous in making their restoration as close to original as possible, resulting in beautiful machines restored to as close to original specs as we know original is supposed to be. Others, such as myself, like shiny, so these overly shiny finishes are not "like original." For me, the end result is what the owner wants the bike to look like when the job's completed, that's the satisfying reward of individual choice. No matter what choices are made for a restoration's outcome, my interpretation of original is, as i have heard others say, "Original is only once, before the bike comes out of the factory crate." Hope this helps, will be good to hear what other members say !
PS - Save those Lotus Root baffles, they are RARE !