Unfortunately the roof sail panel molding are not reproduced for the 1958 to 1960 Thunderbirds. Your only choice it to have the pieces rechromed. The plating of the 1958 to 1959 sail panel moldings presents a challenge for the plater as they have extreme difficulty getting into the deep groves of the panels to fill and polish them. Consequently for even the price the rechromers charge - $250 to $450 a panel, they cannot guarantee that the pits will not be visible in the grooves. The pieces usually come back with plated pits in the grooves.
You can spend a lot more money having the pieces rechromed with the pits filled or you can do the following easy fix. The grooves were painted a semi-gloss back at the factory. You can recreate this look cheaply and easily while covering the pits at the same time. All you need is some Black Matte 1/8 inch diameter graphic art tape that you can buy at Staples or other office or art supply store.
Clean and prep the grooves with isopropyl alcohol or Eastwood's Pre prior to placing the tape in the grooves. Cut with scissors the tape at an angle to fit the forward edge of the groove, then tack down an inch or so of the tape using the tip of a retractable pen with the pen tip withdrawn. Next roll out the length of tape required to cover the groove being careful not to pull on the tape too hard causing the forward end of the tape to shift. Flatten down the tape using the pen. Cut the end of the tape off with a sharp razor. Do each groove in turn. If you have difficulty having the tape to stick, use rubber cement or high tack spray (3M or Permatex) in the groove as a prep.
This is the finished result: