Phil's dead on. NiCrMo-4 is the matching chemistry for C-276. Although, for severe services sometimes higher alloy fillers are used to compensate for loss of corrosion resistance in weld metals. For example NiCrMo-7 (C4), or NiCrMo-10(C22), or if you really want to be safe NiCrMo-13 (Alloy 59) or 14(686CPT), though these last two are probably overkill, and I believe 10 is more popular than 7 when overalloying for 4.
Check with your the manufacturers for specific application and service advice.