Last I played with 68k target gcc it was back in the 2.95 time. Back then gcc produced far worse code for 68k than SAS/C. I don't know if things has changed since, but in general -O2 with the flag specifying the CPU target (in this case -m68060) is usually the best choice.
I think the geekgadgets build I used was 2.95 and I found that building for 68000 with gcc was quicker than any sas/c build & any other gcc build. At the time gcc probably didn't know to avoid 020 stuff that was removed in later processors.
