Where do you get the number 198Hz?
The Hz refers to the refresh rate of the sound driver. For 198Hz, the main loop of the driver has been called 198x in a second. This depends on the FamiTracker replayer code and not necessarily the processor. The refresh bytes in the NSF header (or FTM header) tell(s) the emulated player or hardware player how many times to recall the main loop a second; not how much to overclock the processor. An emulated player, like NSFplay, doesn't have to add additional code to the emulated hardware to play the NSF. Unfortunately, NSF hardware players have to read NSFs and that involves coding something to read and play the NSF. This can draw more from the resources than just emulating the sound on a modern platform.
Even so, speaking from experience I've run 240Hz NSFs perfectly on hardware. I suspect even 360Hz NSFs will play fine with the PowerPak replayer.
Also take this into account. If it sounds OK in NSFPlay, it should work fine in hardware as a ROM. Remember, the NSF header does NOT tell the emulated player to overclock its emulated ~1.79Hz 2a03. So if it plays the way it should sound, chances are it will likely work on hardware -- if not as NSF, then perhaps as ROM. Either or, potentially playable and renderable from hardware.
You also say SuperNSF is a blacklisted tool. Are you saying using PCM is banned as well? SuperNSF is also open-source. I could change a few things and rename it as NotSuperNSF and get away with using it. (I've hacked it a few times already.)