From everything I’ve read, it’s literally 4 bolts to attach a gear drive pump to a motor. I’m sure someone like @SchertzServicesLLC or someone else could walk you through it or at least help allay your anxiety over the process.
You’ll be quite happy with the upgrade from 4 to 5.5 gpm.
Btw, you can get your tank to fill to the brim if you install your hudson valve like so:
Then install an elbow on the inside of your bulkhead fitting, and point it down at an angle. That will allow you to draw your tank practically empty.
As pictured in this post:
