The std 941 pump is very underated, and the 044 very overated, it is fractionally better than the 941, according to the flow charts.
Anyway both consume 18amps/13.5 volts at full flow.
The reason for the loom change is nothing to do with the power, it is the age of the original wiring, all wire builds up a resistance over time, connectors make this even worse, and 20 year old cossie looms can be hopeless.
It is all fine doing a voltage check whilst stationary, but needs to be done under load, a drop under load to 8/9 volts is not uncommon, so this is the primary reason it is replaced.
That 941 pump you picture is the std pump and will be more than adequate, just look around for best price, but at least with msd thier post/after sales etc is spot on.
tabetha