default or selected kernelversion does not have config value CONFIG_SND_GUS_SYNTH.
Result is shown for kernelversion 5.19-rc1

CONFIG_SND_GUS_SYNTH (not configurable)

configname: CONFIG_SND_GUS_SYNTH

Linux Kernel Configuration
└─>Device Drivers
└─>Sound
└─>Advanced Linux Sound Architecture
└─>ISA devices
└─>SND_GUS_SYNTH
In linux kernel since version 2.6.20 (release Date: 2007-02-04)