So, the reason for that change was quite well documented: the old
version ran about 10x slower.  I even proposed a more general
solution, which none of the people who bitched about it at the time
bothered to implement: move the mknods into shell functions, and
provide two implementations of those functions, one using shell
arithmetic and one using expr.

With very slight tweaking, you could even have it switch behaviours
with an option, so you don't have to modify the script at all to run
it.