Another possibility - given we're not worried about originality, but only a similar look to an original - would be a Carson top. This is the type the hotrodders use. Basically just a fixed frame with the fabric permanently stretched over it. The entire thing, frame and all, would lift out. Google it and you'll see some examples.

Hey Curt!
I am a Hot Rod fan even and have never heard of a Carson top! Obviously not a hard core fan :) Good idea, and certainly one to consider. Man, I have to say that original Green Targa is truly what it is all about...beautiful car.

Any experience witht he quality of the Autos International tops? ANyone ever seen one?

Dave - Haven't seen their top, but they have an excellent reputation with everything else they touch.