Brooklands built the earliest 1000 series cars. Probably 12 or so? North Devon have built the later ones. The Brooklands cars have a more subtle rear flare like the early comp cars while the North Devon have rear flares like this car posted earlier:
I think North Devon is using a fiberglass 4000 body for their buck, and I think they look great. The chassis is also built like a fiberglass 4000 with a rear sway bar and the little "nibbles" lasered into the half shaft holes, front shock mounts, etc to mimic an original 300 series car.
I built 5 of the Brooklands sourced 1000 cars and they were very nice cars. Never built a ND car, but hopefully that'll happen