When i ran the Yoko's i was running 205 and 225's (stock sizes for 16's). The SP8000's i was running 225/245 16's. The car handled great with that setup for the last event. This season i am going to 225 all around. The wider tires in the front were really nice as i was able to brake just a little harder without locking up the fronts (turbo brakes and no ABS). The same day i corded the Yoko's i flat spotted the fronts really badly.
Its really very subjective what is 'best'. I would talk to the guy who does your alignment assuming he has some experience with 944's. The guy that has a DE prepped 951 and does plenty of 944's.
BTW, even with the offset tire sizes the car handles very well, i noticed with the 225's upfront i was getting much less understeer. The 205's are just way to narrow i think. The car still rotated very well with just a touch of thottle and i learned to trail brake to improve rotation even farther. The 225/245 setup felt the same characteristics of the 205/225 setup, just with less understeer. 205's are probably a better match for a car that weighs 400lbs less.
I also had significantly less tire spin (no LSD) with the 245's. Yes, 147hp can break the tires loose exiting sharper turns!
.