You can still use AttnFlags, but you might have to #define the value:
#ifndef AFB_68060
#define AFB_68060 7
#endif
#ifndef AFF_68060
#define AFF_68060 (1<
#endif
I believe this only works if the 68060.library is installed. As for speed, timing a known-cycle (per CPU type) loop seems to be a way to do it, but you'll need to ensure the instruction cache (if present) is enabled.
Piru would be the man to ask as his WhichAmiga tool detects the entire gamut of m68k amiga configurations.