Since the Ionic team made the switch from webpack to gulp, we had to go through and convert some projects to the gulp based build. Our team worked through the transition and came up with a simple list of steps that you can do to make the change.
Looking for the solution myself, I seen plenty of people with the same issues. So I decided to post how we go about doing the transition.
I will try to help anybody that has issues. I hope this guide is helpful.