I had one for many years.It was reliable enough,but not exactly quick.Top speed,sitting normally,about 70 - 75. Happy cruising speed 55 - 60. 6 volt electrics,so poor headlamp.Some had a distributor type gadget for the points,later ones had the points in the cases. 7 to 1 compression ratio,from memory.Easy starter,I went everywhere on it,including my first trip to the IOM.It was popular for despatching in the Army.There was a tuned version called the SS90,with a higher compression ratio,but I know nothing about that one.I would keep it standard-it will run happily for many miles.I remember once the gear lever fell off,but I didn't notice until I tried to change down a couple of miles later.I pulled over,clutch in,turned around and plonked away back up the road to look for it,all in top gear.Try that on an XBR.It's probably similar in performance to an Enfield 350.