EK008 KSS/KTS ENGINE

I have an aspin rotary valve Velocette engine with the no.KNSS 3281, Can you let me know how old it is?Also the drive shaft from the oil pump verticaly to the valve gear is mising some sort of coupling,Both ends of the shafts have a slot,I can make something up but can I buy a ready made part? Every thing from the crank case up seems to be different from other pictures I've found on the net I guess it may be a special engine. Hope to have it running soon. - Andrew King 24/3/2005