So here's where I landed with the lettering.  First the letters were painted in a darker brown and then overpainted with yellow ochre and few highlights.  The goal here was not perfection as I new that was not going to remotely close, hopefully "impressionistic" describes it.  Was very happy with the outcome, may touchup a little more but I'm forcing myself to stay away for now.  The placement may look a little odd, but I had to estimate where the decorative rails will be so it should be correct