The two FCAW filler metals that would be avialable for this welding operation are E410TX-X and E410NiMoTX-X. The 410 should be tempered at the same temperature as the 410 base metal, but if the 410NiMo filler metal gets tempered above 1150F, then it needs to be re-tempered at 1100-1150F (approx) in order to eliminate any untempered martensite that formed during the first temper. If you can temper the whole assembly below 1150F, it could be done in one cycle. The main difference in usability, is that the 410NiMo is tougher, and less crack prone than the straight 410. ER410 and ER410NiMo are also avialable in solid wire for GTAW root passes.
There is nothing wrong with the filler metals being currently used though for this application. (Except for lower productivity of course.) However, there are even some nicke based FCAW wires being manufactured now if you have to stick with nickel based filler metal. The NiCr-3 is a common substitution for NiCrFe-2 when switching to GTAW or GMAW from SMAW, so that is not a problem either.