I don't have my mc68060 book here, but I thought the
introduction said it handled all mc68020 instructions.
Is that not the case?

If not, which mc68020 instructions don't work?

In all my experience with m68k boxes, the mc68020
instruction set has always been used as the "least
common subset" that one uses for code that should
run on all m68k CPUs. *

(* "All" being defined as mc680x0 for x>=2
   because mc68000 and mc68010 are so rare
   as to deserve speical treatment:)