Even though the FM 90 is a copy of the Browning Hi Power, there could be dimensional differences that wouldn't be obvious in photos. A few thousands of an inch could make a big difference. Even if it were an exact copy, the barrel would probably need minor fitting. The only way to really find out is to purchase one and see how it fits.
I once tried this with a Beretta 92 and even though the barrel fit and functioned properly, the slide closed a little too far foward on the frame.