I don't think it's too bad job, though I have no personal experience.  The worst thing would be the difference in the track as the Crown Vic is wider I believe, so it might require reverse offset wheels.  There is a guy not too far from here that advertises a kit on Craigslist for the conversion, though again no personal experience with the guy or the kit.
http://sacramento.craigslist.org/pts/4944720530.html

Don

You will have to graft the whole front frame on to your truck, not an easy job.

I have a 1960 f100, have a chance to get a 2008 crown vic front suspension, is it a good year to use with truck, thanks guys