It should function in that position, my asking was mainly because I'm not sure what the benefit of changing it would be. That resistor sets the current that comes from the power supply and runs through plate of the tube. Its resistance value accuracy and stability are its most critical attributes , and in theory at least it's isolated from the signal path. I'm just not sure if a tantalum resistor is an upgrade for a current set resistor or not. You won't harm anything trying it.
