The IIgs is basically nothing like a Super Nintendo other than sharing the CPU. Developers used the IIgs to get familiar with the CPU and work on game logic before the Super Nintendo development platforms became widely available but *by no means* are the systems even remotely enough alike to allow a fully-developed game using the SNES's custom video and sound CPUs to work.
(It's a bit like asking if a software emulator could get a Neo Geo arcade game cartridge running on a Macintosh Plus because, after all, they both use Motorola 68000s. The fact that the Macintosh Plus only runs at 2/3rds the clock speed of the Neo Geo is the very least of your problems. Overclocking the Mac isn't going to help the problem much since you're still comparing a single-CPU system with simple framebuffer video to a highly engineered console with *two* general-purpose CPUs, an immensely powerful sprite-based video accelerator, and a 15 channel sound chip. The gulf between the IIgs and the Super Nintendo's hardware is similarly vast.)
(It's a bit like asking if a software emulator could get a Neo Geo arcade game cartridge running on a Macintosh Plus because, after all, they both use Motorola 68000s. The fact that the Macintosh Plus only runs at 2/3rds the clock speed of the Neo Geo is the very least of your problems. Overclocking the Mac isn't going to help the problem much since you're still comparing a single-CPU system with simple framebuffer video to a highly engineered console with *two* general-purpose CPUs, an immensely powerful sprite-based video accelerator, and a 15 channel sound chip. The gulf between the IIgs and the Super Nintendo's hardware is similarly vast.)