I'm not sure. For most instructions the 68000 only accesses the bus every two cycles, where it fetches 2 bytes. I am too lazy to check, but it would not surprise me if the 68008 accesses the bus on every cycle. So it might not make much difference.
That would be reasonable, but I always thought the 68008 was just an ordinary 68000 with only 8data lines exposed, thus is would also suffer the every other cycle memory access penalty.
-Edit- But actually thinking about it, that would make almost all the addressing modes pointless...