I don't know that any were that color in period, but I think it would work well. There was one yellow one (for the bleepin' blinkin' bloody Belgians) which was since painted silver.* Two shades of blau—light and lighter. One was Swiss red (which, surprisingly, doesn't work, to my eyes). The British teams (green the official color) tended not to get Porsches for some reason.
As race cars, these babies got repainted a lot: Repainted, re-bodied, re-powered, re-just-about-everything'd. I'd be frankly shocked if there was never a green "original" 550 RS screaming up some forested Scottish hill or around Goodwood in the years before they became "iconic" and fit only for preservation or restoration to "precisely original specifications."
I like this color and think it'd look great on a Spyder, just as it does on a 911. But I like green generally.
The other great thing about going green is it'll prevent you emerging from the pub and trying to drive away in the wrong car.
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*After being re-bodied in fiberglass as a coupe and then re-rebodied back to aluminum Spyder status.