We have Falcons with 5-speeds here, but I don't know if the bell and flywheel are different between the 200 and the 250 etc...
The 5-speed is a Borg-Warner used right through the industry in Australia, Ford versions are readily available.
If not, our 200s came with the B-W 35, which has a removable converter housing. You could make an adaptor out of one of those, which is the way my brother used to always adapt 5-speed Toymotor boxes to all his Fords.
