Well, it's an improvement over the carbed version of the 280. If the k-jet is an early version it's quite simple and bulletproof, much less troublesome than the dual carburetors. Hall Ignition is also trouble free, no points to replace. Set it once and forget about it. Hydraulic lifters also save you time as you don't have to adjust the valve clearance regularly. And 188hp is also a significant power increase over the 280S motor.
Advantage is less over a 280SE motor as difference in power is less significant, Mechanical injection is much less troublesome than the carbs and a Pertronix ignition will get you rid of the points. You will be left with valve adjustments but hey, that's less work than an engine transplant.
So if you have a 280S with a blown engine and an M103 lying around, why not. But then why not going for an early 5.0L euro M117 motor: More displacement, lighter engine, better car balance, more power, as simple and as little maintenance as the M103 engine, for similar transplanting work. More bang for the buck.