A lot of the fonts you mentioned, like Zapfino, aren't designed to be handwritten -- they're typography fonts.
And you're not going to get the thick and thin lines from something like Italic from a regular nib.
The best bet is going to be looking at standard hands such as Palmer. Or, if you really want to do something like Italic, you're going to need an italic nib. I don't know how easy it is to swap nibs on your pen, so you may need to either have the nib reground or just buy a different pen. If you don't want so spend a lot of money, look at something like a Lamy Safari or Pilot Metropolitan, and get one with a stub nib to see how you like actually writing with it.
The advantage to the Metropolitan is that they run under $20 US; the Safari will run you more -- roughly $30 depending on where you get it. Plus of course the cost of converters in each case. But the advantage to the Safari is that it's really easy to swap out nibs on them (figure another $10-15 each for nibs; so you can get a pen with a stub nib and then buy a regular nib for other writing).
A low end pen with an actual italic or stub nib is going to be less expensive in the long run than getting the nib reground, or seeing if you can swap the nib out directly from Montblanc.
Barring that, I'd say go buy a really cheap Speedball dip pen in an art store and practice with a variety of nibs until you get the look you want.
Ruth Morrisson aka inkstainedruth
"It's very nice, but frankly, when I signed that list for a P-51, what I had in mind was a fountain pen."