First of all, how wide are the 740 rims?
Without knowing that, a few general comments:

1) the bolt pattern on the 740 wheels will fit your car.
2) the 740 wheels probably have slightly greater "offset" which means that relative to the existing rims, the new ones will sit about 1/4" in toward the center of the car (the whole wheel will be moved in 1/4" on each corner). This is rarely a problem.
3) 16" wheels should clear ABS brakes on a 240.
4) The main concern will be to choose tires that have a similar diameter to the tires you have now and an appropriate width so that they will fit your rim. This will likely require a 50 series tire, something like 205/50/16 or so. You'll have to check this on a tire size calculator. I like the one at:

http://www.1010tires.com/TireSizeCalculator.asp

Going wider than 205s *can* cause serious fit problems in 240s, since the tires may rub on the inside our outside edges, especially when fully loaded or when making a turn, although many people on this board have done this. It all depends on the exact package of rims, tires, and other suspension modifications on your car. But 205s are likely to fit these 740 rims.
Check the rim width, and, if you have access to the wheels, check the offset also, which is marked on the rim. Volvo rims have a spot somewhere on the outer face of the wheel that lists width, diameter and offset in that order. If you're confused just write it down and post to this board.