Thanks for all the wonderful comments, going to go with Robin's recommendation of burnt umber, that sounds the most prototypical. Most do black and it just seems to blend into the background.
Eric, drove up to the Hobby Gallery, they had some Central Valley items but no girder material. Shelton RR, gave up going over there, never could figure out their hours. Have several hobby shops here in Milford but they are more interested in stocking military items.
Pat, sorry, did not get your e-mail. You are entirely welcome, hope the mold and letters work out and fit the bill.