I've always used the woven liner you can buy at any antique auto or hot rod supply house, but I see Bob Drake has a new rubber styly adhesive backed liner that looks like it would work well.

He also sells some shims but they seem a bit pricey. I just get a bunch of front-end alignment shims to shim different areas of the body to line up door and hood gaps, reveal lines etc.

You will find there is a lot more to mounting the body than just bolting it down on the frame and to get everything lined up correctly sometimes turns into quite a chore.

Mick