@Hattig The ARM 2 was very powerfull chip. Clocking in at 4 MIPS easy, VS the 68k 1MIP. But these are RISC MIPS, ARM2 had a much simpler instruction set (roughly one third the 68k), where you need to combine some instructions to equal one 68k CISC one. So some your throughput on MIPS are combined instructions. Rough comparison might x2 as powerfull. I would not say any more than that.
Yep, ARM2 appears to have around 35 instructions, so less than the 68000. Of course with predication you don't need some branches in the code, and you also avoid separate shift instructions as they're built in (and that also reduces the instruction set). As an aside, the 68000 code will be more compact because ARM uses 32-bits per instruction, and 68000 starts at 16. It took until Thumb2 for code density on ARM to match 68000.
We could use benchmark MIPS - like Dhrystone, although of course these have flaws too) ARM2 could get 0.33 DMIPS/MHz (so 2.66 DMIPS for an 8MHz ARM2). I'm having difficulty finding 68000 figures though, although I did see 0.2 DMIPS/MHz for the 68030 mentioned, which could let us assume ~0.1 DMIPS/MHz for the 68000.