Best FNUM values depend on what you are going to do, but FNUM values do not depend on octave (block), unless you want to go below octave (block) 0 so the you have to halve the FNUM for example. I would reserve the MULT multiplier as timbral characteristic for an instrument instead of using it for setting octave. So basically each instrument could span only 8 octaves, but the multiplier defines the "base" octave.
The chip has a setting for what range of FNUM values you would like to use so it knows how to interpret the FNUM values within an octave to correctly apply rate correction.
I would use 14318180/288 as the Fs in a spreadsheet, and of course 440Hz is the A4 frequency, so this makes A note as FNUM 580.
Basically the higher values you use the closer you get to the actual note frequency. So thus I would use the FNUM range of 512 to 1023 for an octave.
Thus the values are : 517,547,580,615,651,690,731,774,820,869,921,975
But this has one downside; the values are such that when the octave is divided into upper and lower halves based on bit 8, the the notes get divided unequally, 7 notes in low half and 5 notes in upper half. Usually this is not a problem.
If you want to use the other setting, where bit 9 defines the split point, and you want to divide the octave into 6 notes in low half and 6 notes in upper half, the values are:
365,387,410,435,460,488,517,547,580,615,651,690
And you still get highest possible FNUM values.
Of course there are other ways as well, this was just an example.
