I suspect that my bike is one of the one's that L.A.B. has identified as an early roadster. Although the exhausts have been replaced with a two in one the last owner kindly sent me the original pipes and mufflers - at least the ones that were on when he had them. They are roadster pipes, and the original brackets to which the mufflers are fixed are on the bike. Given that the rest of the bike was reasonably original I suspect that this was actually a roadster rather than an S; I do agree that the S looks terrific. My original pipes fairly rough, but I now have a chrome plater who owes me money and I might see if I can twist his arm into replating them (I understand that a lot of platers are reluctant to put exhausts into their acid baths).
As it happens I have just returned from the registration certifiers, with a number plate and warrant of fitness. The process has taken about 3 weeks from start to finish; the bike originally failed because it didn't have indicators, and was first registered in NZ in 1986 - it is a 1970 model that was imported from North America. Under NZ law all bikes that were first registered after 1976 have to have indicators unless they are exempted by certain paperwork. Ironically, the paperwork is a certificate from the Vintage Car Club of NZ, which I obtained by filling out their forms certifying to the Vintage Car Club that this is a 1970 bike, and sending photos. Upon the basis of my certification to the club, the club issues a certificate that the bike is a 1970 model and is exempt from the requirement to have indicators, and that is acceptable to the government appointed registration certifier. Of course the original certificate has been lost in the Christmas post, so the club emailed me a duplicate of one but not all forms today; and the certifier registered it against my promise to get him the other forms as soon as they arrive. High stress all round.
As I pointed out to the certifier, we could see the id plate on the steering head with "June 1970" stamped on it; but he correctly pointed out that the regulations required the process that we went through; another $100, and a very stressful delay given that I am taking the bike on a trip to the Coromandel peninsula tomorrow; I would have liked a bit more time to ensure that all of the kinks are ironed out before I go.