Instead of "G", on an Altair 680 you would jump to a specific address (ex. "J 0100"). But SWTPC software probably would not work on an Altair 680 without patching. While they both used the 6800 processor, they had different ROMs and different a memory map and subroutine layout. Much SWTPC software is calling MIKBUG subroutines which of course would not exist on an Altair 680.
I noticed on the other thread you referred to my emulator as an "SWTPC/Altair 680 emulator". It is not. It is an Altair 680 emulator only, not an SWTPC emulator.