have to Bleed brakes when replacing Check valve?

[bigbird189]

I have 94 F350 Powerstroke Single cab. I think my brake master cylinder is going bad but I heard some one mention to change the brake check valve first. My brakes are very spongy. Now my question is do I have to bench bleed or bleed my brakes if I replace the check valve? I know I have to do bench bleed the master cylinder if I replace it. Also When bleeding the brakes, do I have to bleed the each wheel starting from the back farthest from the brake master cylinder?

Does anyone have a how-to write up for OBS? It seems pretty easy but have never done one before.