For the most part, all the chemicals of the black & white process are compatible. A 400 speed film, in my opinion, is not all that “grainy”. That being said; if giant prints are the goal, then use 200 or better 100 ISO. This is because slower films contain less silver. The grain you see is a clumping of metallic silver in the emulsion. A 400 speed film developed in a fine-grain developer does quite well.

A fine grain developer likely contains a mild silver solvent that reduced grain size by dissolving away some of the silver clumps. One trick of the fine grain developer is to stain the image giving it a slightly warm tone. The warm tone allows reduced developing time while retaining printing density. An olive tone acts to filter out some blue and UV light. This makes up for the lower silver content. In other words, the negative has a higher printing density despite the fact that the metallic silver image is abridged. The result is reduced apparent grain.