Thanks for your reply, apparently there is a kit to do this job. Ii will have a chat with Mark, I bought my fluted CCM engine covers for my Cheney from him. nEB has a conversion with cast iron barrel but price is horrific.
Anyway scored a cheap B44 engine that needs reassembly so figured I would do Marks clutch conversion seeing the motor is in bits....I need new piston so thought of the big bore at the same time. Now all I need is oil in frame BSA frame....I picked up Rickman kit that is designed for BSA frame , that is tank and body work etc along with a bolt on sub frame.