Hi Tindrrel,
Great looking bass. The ib-5 is a great kit (I am still building mine)
I would take the time to recess the rear cover plate, makes the world of difference.
The jack output was tight on mine as well, but didn't take long with a round rough file to make it a nice fit,
or use the dremel bits as Stan suggested . Just take your time and enjoy the build.
Maybe not as long as me.