An English bottom bracket has a diameter of 1.37 inches, or about 34.75 mm -- about a quarter millimeter smaller than a French bottom bracket shell. I'm afraid there might not be enough thread depth after tapping to securely hold an English bottom bracket.

Tapping to Italian might make more sense. Italian bottom brackets are 1 mm bigger than French. You'd just have to account for the difference in shell width. French bottom brackets are 68 mm and Italian ones are 70, so you'd need a 1 mm spacer on each side. Would this work for your particular crankset? I don't know and would have to defer to someone who knows Shimano two-piece cranks better than I do. (Is the spindle the same length for English and Italian? Are the cups the same depth?)