Thanks for the info chaps. Looks like my cunning plan of slowly collecting the bits to turn the J1 into a J1/N (Gipsy engine) or a J1/S (O-320 engine) have bitten the dust then
Maybe the O-200 option is better as, being the same horsepower (theoretically) as a Cirruss Minor II it won't need the bigger struts and vertical tail that the bigger engined versions need.