I used the trunk lining kit from CARS, Inc. which I purchased 9 years ago. At that time I went with this kit because it was substantially cheaper than the kit from Clark's Corvair. It was also cheap enough that if it did need to be replaced it was not a big deal. In fact it has only gone up $10.00 in price since then. It was a 5 piece kit that included the spare tire cover. The main piece that lays on the trunk floor has a hard fiber board backing to prevent the indentations from the trunk floor showing through. I am very happy with it. It fits well and I don't remember having any trouble with the pieces that go on the wheel wells. Part number: TM65R
There was no way I was going to be able to get the old trunk liner off. To prevent any bleed through or staining from the old liner I covered it with a thin rubber membrane that I purchased on e-bay.
For the cardboard kit I just purchased a cheap one on e-bay and covered it with vinyl. I wanted to cover it with vinyl to prevent it from getting beat up and easy to clean. Instead of grey I went with a tan to more closely match the trunk lining. If you should decide to cover the cardboard with vinyl make sure you test fit it in your trunk before you apply the vinyl. I had to do several test fits and trims before applying the vinyl. To apply the vinyl to the cardboard I was advised by my upholstery guy to use heat activated contact cement.
Bill