I see you will be releasing the NS F7 A & B unit soon. Are there plans to produce the other two F7 A & B road numbers in the near future? I don't like renumbering locos unless I really have to.
B-mann's white paint erases pretty easily. I do not know about the gold. Maybe someone else here, does. Changing numbers is not hard. A common eraser on the end of the pencil used carefully will erase the number sufficiently so that a new decal will obscure everything.
I have changed numbers on more than a few locomotives and rolling stock over the years. It is not difficult.
I have used comet cleaner and a peace of soft wood.Mix up a paste and rub it on the numbers.It seems to work well,but some times leave a shiny spot on the paint under neath.