You might ask or search down in the RT/10 - GTS forums below. I think I've seen that topic come up several times there, but I don't recall any brands off the top of my head. The name Unitrax comes to mind, but I think they are more halfshafts and carrier unit swaps, not necessarily rings and pinions. I know Yukon seems to be fairly well regarded as well in the differential world, but don't know if they carry the Viper parts and I just noticed you're not based in the States, so not sure what availability or shipping would be like.
I put 355s in two of my past Viper‘s. A gen2 and a Gen 3. I was satisfied both times. My thoughts on the 373 would be really poor gas mileage and top end would suffer too much. The first one I bought the ring and pinion from Viper Parts and the second I bought just a standard ring and pinion for a Dana 44 rear. No noticeable difference.