When my ITR fuel pump failed, I replaced it with the standard 4 lbs fuel pump from Napa. However, I was able to mount it inside the case were the original pump was mounted with the use of a few extra pieces of brass pipe and elbows.
Regardless of were you mount the replacement fuel pump, if your original one fails, the Napa fuel pump, fuel filter, and air filter work as good as the ITR parts for half the price, and they are readily available almost everywhere. However, the igniter and nozzle are only available from ITR.
The bottom line is that the unit can be maintained inexpensively, if you are willing to put in the effort to overcome the learning curve and get your hands dirty occasionally.
Gerald