the 74 also had bad brazzing on the fuel tank witch could leak. they were a factory recal item, if you could actualy get a volvo dealer to replace it now is a different story. good news its the same tank as the ones on 240's.

the suspention is the same as a 73' exept for the panhard bar witch has the same mounting point on the chassis as a 240. but the axle mount for the bar is the same as early 140's , so its 74' specific. i've never seen one break ever.

as far as the k-jet basic system on the car, i found it very easy to work on, but i worked on it for the last 15 years. to do tuning and testing on k-jet you only need 2 special tools besides basic hand tools. a decent multimeter for testing wiring and sensors, like the thermal time switch. and a k- jet specific fuel pressure tester. if you cant find one you can easaly make one for less than $80 .
i would also recomend getting the haynes fuel injection book for bosch systems.

best of luck
fidel