In general, you take a normal scene and develop N-1 and use a higher paper grade or filter to print.

That's a general reciprocity idea.

You figured that you are on the straight line. So you could develop Normal and use the same paper grade or filter as if you had exposed normally. The contrast should be the same as you would have normally gotten. You would develop less if you expected a longer than normal scale subject would have shadows still at 0.3 and highlights at 2.1, but yours isn't going to have a thin shadow.

You will have a density 1.05 to 2.1 if you develop normally, and the only difference from a perfect normal negative that you would print for 16 seconds is that you will print this one for 40 seconds.

I am generalizing however. You will have more grain. To reduce that, your original plan to develop N-1 is fine.