As far as I know Dave, it's one of those "either/or" kind of things. I think it all depends on the look a Triton builder prefers. Some like the look of the external springs, while others prefer the internal spring look.
On British motorcycles the external spring forks predate the internal spring variety, and so the builders of Tritons and other Cafe Racers may like the older look and that's probably why you'll see those a lot of the time.
My guess is that the builder of this T-Bird Cafe Racer probably likes that look also, and so he probably added those external springs "for show".
