The 7000 fiberglass cars like Ron said have been made in very low numbers. They along with the early 4000 fiberglass cars were the only Shelby cars made 100% by Shelby frame body etc. Aluminum cars in 7000/7500/8000 were made by AC or KMP and some others.
Are the fiberglass cars still available and made by Shelby, not sure. Aluminum would most likely come from KMP (body and chassis only). I do know of a company making original style fiberglass 289 FIA’s they just finished their first unit. They are supposed to be for sale here now.
http://www.youtube.com/watch?v=xZFcpYSnUCE
What car drives better, IMHO hands down the 7000 cars are the best handling. They are a real joy to drive, no heat, plenty of room and they will hang with any big block. That is why I sold the 4000 and kept the 289.