I recall reading on the BSA page that there were three types of Super Rocket each year, UK, East Coast USA ( same as export bikes to other countries) and finally West Coast USA as demanded by the big Californian BSA Dealer, Hap Alzina.
The UK bikes had less chrome than the East Coast USA bikes but the same compression ratio. I believe it was 8.3 to on in 1962, however different articles list slightly different numbers.
The Hap Alzina bikes after 61 were 9 to one. They also had the peanut tank, more chrome yet and cowhorn bars, all to suit the California Hot Rod style of the day.
Of course my memory could be way off on this. I did quite a bit of reading on that site about two years ago when shopping for a Super Rocket.
Glen