The english/iso headset will work just fine, the threading is really close to italian, thats why u can do it. The only difference is the angle of the threads but the pitch is the same 24 tpi. Thats why it works.

Well , if you are one of the guy that changes headsets in the same bike like 80 times per year at some point the frame will give up and then the problems starts, if you are going to put a headset and leave it there even after you sell the frame just put italian or enlgish headset wont destroy the bike at all.