Pinpoint is the correct grain for the vinyl convertible top. The rear window should be clear vinyl with a small pinpoint skirt at the bottom of the window. The top pads can be a universal style and can be trimmed to fit. The universal style is correct on these cars.
The carpet was a cut and sewn style in a loop configuration. While some GM cars had a "Tuxedo" weave which had black specks woven into it, the Roadmaster did not. You might try Auto Custom Carpet (ACC) for the carpet kit. They do a very nice job.