Not as easy as you would think, because compared with the 144, the 240 has a different seat mount cross-member above the floor.
If you're lucky, you might find that the 144 seat mountings/sliders could be fitted/welded to the 240 seat frames.
That is basically the technique I used to fit Alfa seats to my 245
http://www.volvoforums.org.uk/showth...159425&page=31
John