Since most of these obscure scenarios lack source material, as well as a lack of action, you're probably better going for one of the following:
- The battle for Berlin
- The battle for Stalingrad
- Omaha Beach
- Hedgerow fighting and the road to Carentan
- The battle for Arnhem
Unsurprisingly, all of these have featured in at least one of the WW2 fps games out there.
Stalingrad is by far the most exciting, a clash of over a million men in an area about 20km square. The street to street fighting would be difficult but most likely possible in FPSC. The sniper battles would also be a nice feature.