For your 1987 Chevy conversion windows, we offer custom pleated shades in gray that can provide enhanced light blocking. You can choose between Night Only (complete blackout) or Day & Night (light-filtering and blackout) pleated shades. The dimensions you provided—42 inches wide by 27.25 inches high—are perfect for a custom fit. To address your concerns about the bottom rails and mounting, we can design new bottom rails with altered screw hole spacing to cover existing enlarged holes and reduce rattling without requiring larger screws. We also accommodate your preference to mount the shades inside the plastic conversion window frame with minimal new drilling and no external mounting hardware. We recommend sending us your existing shades for precise measurement verification and to expedite the manufacturing process. We will not proceed without your final approval to ensure the shades meet your specifications and installation needs.