Eric - they should have some balsa but basswood works better, a bit tighter grain. i use it for 1/35 and 1/72 RR ties. another trick for chain and rope is to take a figure. you know what the real stuff would look like in your hand so lay the thread or chain on the figure's hand and see if it looks to scale.
i have one of those flatcars from 8 years ago partially done. may be time to dig it out and see if it is salvageable. also we have a RR Group Build in the group build forum if you want to join.