Transit flywheel with machined to fit a Sierra flywheel should be able to take 240 mm clutch. Actually now reading this from Skogenracing I recall reading about this modification on another forum too, just needed to help my memory a little bit.

Or if I can't find a Transit flywheel, blingfactory.fi also sells new Pinto flywheels for 240 mm clutches. Quite expensive, but still a possibility at some point.