I would use #2 if it is closer, but still slightly larger than the chamber.

CIP specs tend to be quite oversize in head and sometimes neck dimensions, making for over-sizing/over-working the brass. With expensive brass, you normally do not want that.

What is nice when ordering a wildcat reamer, is getting what you want, measurement wise.

I have always had good luck with Dave Kiff, of Pacific Tool and Gauge. That said, I know nothing of the .404NE, except that I've wanted one since I was 15yrs. old.