The A64 emulator is the only option for slower Amigas. It ran at full speed on my A4000 with a 030 @ 25MHz.
However, just like you said, MagiC64 or Frodo is a lot more fun.
I used to have a 1541-II connected to my A4000 (and my A500 before that) through a special adapter. I used that with A64, and Frodo 2.4 I think and it worked very well, but only for programs not using a turbo-loader. Those where the days... :-)
