You'll need to replace all four bracket parts that mount the 760 grille AND the 760 headlights....and then you'll find your 760 grille is narrower than the power hump or whatever on the 740 hood! Plus your 740 lights won't fit on the new brackets so you'll have to put on 760 lights.

Here's a pix of my car with 760 euro lights and grille on a 740. I don't think there's much diffo between 90 and 91 740 (but I may be wrong so there.).