gavanized nub too long/short

Hi --I'm installing a Kohler shower fixture, and they say it has to have a 3/4" nub beyond the finished surface. With a 4-1/'2" nub it sticks out about 1-1/16" (I've really cranked it in as far as I can). With a 4" nub it in principle will be just over 1/2". Is it possible to cut galvanized pipe? Am I better being longer or shorter.

Thanks,
Areselle

First off, I'd not use galvanized at all in this application - I'd use brass. Worse comes to worse, you could get one made to your exact dimensions. Buying a thread cutting die would cost more than having it done for you. A well stocked plumbing supply probably has them in assorted lengths - if you're lucky, one would be a stock item.

While the nipple (it's not called a nub, at least in the US) in galvanized might last a long time, especially if you cut it, would rust.

Thanks, Jim, it's not too late to go with brass, which is what I'll do.

Areselle