I think your problem is you inserted $FF to expand the ROM instead of $00 and thus the IPS patch creator reads $FF as a change and you then create an IPS that's bloated.
I inserted $100000 worth of data using $00 instead of $FF and reimported your SPC sequence, sample indexes and pointer. This produced an IPS a little over 3KB in size using Lunar IPS.
FF7 Final Judgement IPS
I inserted $100000 worth of data using $00 instead of $FF and reimported your SPC sequence, sample indexes and pointer. This produced an IPS a little over 3KB in size using Lunar IPS.
FF7 Final Judgement IPS