Are we talking the original cottered spindle or a modern square-taper symmetrical spindle? I only have direct experience with a cottered spindle on a 1975 Grand Prix, but after attempting to swap a Grand Prix bb and crank onto a Raleigh International (and finding the spacing slightly different - then fitting a square-taper on) I would say that if an International needs a 118mm square-taper spindle, a Grand Prix would likely require a narrower 115 or 112 to obtain a good chainline.