Hi
I'm shure this question was already asked and positively answered in another forum of Amiga.org one or two month ago, but I couldn't find it.
If my brain isn't fooling me, the A500 drive fits into the A1000 except for the knob, that must be changed.
EDIT: Found:
http://www.amiga.org/forums/showthread.php?t=6630Noster