There are no user level ISA changes to the 68060 from the 68020 that a compiler would use or target except an FPU ISA which the 68020 did not have. In other words, the 68060 ISA=68020 ISA for almost all purposes.
68060 has a few less instructions than the 68020, so to be 100% compatible it shouldn't have them either.
FPU & MMU are also required for 100% compatibility. I don't believe gunnar is going to take over the soft core market, which is what he intends to do. What he's created doesn't really fit the requirement of getting us all access to 68060 accelerators either.