There are a number of universal kits available on eBay for $200-$400. I installed one an '85 VW Cabrio years ago. The challenges are:
1) Throttle control
2) Speed detection
The traditional throttle controls are vacuum servos. I don't remember offhand what vacuum sources the 280 has, but I don't remember much. Perhaps the brake power assist and that is about it. Not the big vacuum reservoirs and vacuum controlled ventilation flaps like newer cars. Good news is that some newer CC kits have pure mechanical/electric servos. Getting a "pull point" on that throttle linkage in the engine bay should be no problem.
Speed detection shouldn't really be hard at all either. With that fat assed driveshaft running to the rear, a typical zip tie magnet and pickup should be fairly easy to implement.
The fun part is doing it all without drilling any holes and just fabricating "clamp on" bracketry to fit on existing structure. Looking forward to hearing what Jim Villers has come up with....