I called CarcoverPlanet.com and they said they were a custom/form fitted to the specific car.
For $115 shipped, I figured I'd give em a shot.
Ended up ordering 3 covers for some of my rides.
64 Lincoln (Insert your best joke here)
57 Vintage Speedster
67 GTO
They even gave me a 10% discount for ordering all three!
I gotta say... WOW. Great material and VERY happy with the fit. My cars are garage kept so I went with the cheapest option, however... they have some nice choices for cars stored outside as well.
Direct link to the Speedster cover as seen in my pics here
Link to other cover options for your speedster here
I ended up paying less for all three covers than I would for one cover at California Car Covers.
Just wanted to pass on the info. (who says I don't contribute)