Here is a set of 1970 Impala Skirts, these will fit the the AMT kit.
(it was mentioned by a builder that these might fit the 69 impala kit too)
1970 Chevy Impala Resin Skirts- AMT
As with many resins, you'll need to clean up any excess flash, pin holes and wash down with a good degreaser to remove any oils from the molds. Also before paint, check fitment as resin differs from plastic parts.