The 489 obsession

Buy every cheap 741 you can find. If you actually look at the pinion gears (the supposed weak point of a 741) the small part of all three shafts are the same size (weakest link?) and the 741 doesn't have the potential stress riser of the abrupt increase in size.
As mentioned above, the major drawback of a 741 is a lack of ratios available in new gear sets.