I did the lower lower door pillars first, then rockers, then fitted kick panel, cowl and floor before welding anything else in, and then welded the floor in. I haven't welded in the kick panels yet, but I think I'll do that next. My plan is to keep the inner-to outer cowl piece for last to maintain access for finishing the welds on the kick panel and welds.
Plan on the kick panels to be a pain in the arse. I used patch panels from Jim Carter and needed to massage them seriously at the lower end to make them fit the floor and rocker. I bought the short kick panels and they were closer to fitting the floor, but not good either. Depends on how much you need to replace on the kick panels. I believe Dynacorn has complete kick panels that go all the way up to the upper cowl. They may fit better.
I'm not understanding what you mean by cowl braces.
By the way, I sandblasted first. That way it reveals the stuff that doesn't look bad, but is ALMOST rotted thru, and allows cleaning out all the stuff that'll be concealed when everything is welded together.
