Shimano bb + miche primato cranks = ok?

As it's been mentioned, the JIS and ISO tapers are different shapes

No they aren't. It was mentioned about 100 years ago by Sheldon Brown, and everybody has taken his word for it ever since without bothering to check for themselves. The advice on http://sheldonbrown.com/bbtaper.html is both wrong and self-contradictory. If it were really the case that

If you install an ISO crank on a J.I.S. spindle, it will sit about 4.5 mm farther out than it would on an ISO spindle of the same length.

Confersely, if you install a J.I.S. crank on an ISO spindle, it will wind up about 4.5 mm farther in than it would on a J.I.S spindle of the same length.

then there is absolutely no possibility that it would also be true that

I have a lot of experience mixing ISO/J.I.S. in both directions on my own personal bikes, and it as never given me a lick of trouble.