I appreciate those who are building cars to be as close to original stock as possible. Years ago I helped a co-worker build a 66 Mustang for show. It's insane how much detail and expense is involved in producing a competitive car, right down to the level of orange peel in the paint and over-spray in the engine compartment. It's a real challenge to get those last few points... My take is that unless you are building a car "for show", it's more important to have good looking, durable carpet it is than being 100% correct. On my previous Z what I did was use indoor-outdoor loop carpet. It had a nice backing and did a good job at helping to deaden sound & vibration, but it was a bit heavier. I cut it out myself using the old carpet as a pattern, improving the fit where required. I then had a local upholstery guy bind the edges. I plan to do the same on my current car. It won't be "show" stock, but then I'm not building a show car... While it will be mostly stock, I'm building a "the way I want it" car...