Not sure on that fiero one....its...interesting too. Although I see it comes with it's own patio.
As far as the 1st one, not sure if its even a bike motor. Could possibly be a VW kit type thing.
OK I just did a little lookup on rupp trikes. Seems like they have all kinds of engines.
Pics of rupp trikes finished here:
http://trikes.50megs.com/index2.htmlFind out what motor it has and see the availability of parts then you can tell if it's worth fixing.