There is a flywheel that will accept a heavy duty clutch cover with nine attaching bolts instead of six, and a slightly larger disc, but finding that clutch assembly without paying to have a core item rebuilt is going to be a real challenge. Otherwise, just use any flywheel that matches the starter- - - -139 ring gear teeth for a 6 volt starter, or 168 teeth for a 12 volt, with whatever clutch that will bolt onto it.
Jerry