Big block in Dart: transmission fill tube issue- tried everything! Help!!!

We have jimmy rigged the wrong fill tube for the tranny on their temporarily 2 years ago, it leaks out the bottom and is the wrong size and measurement...

The correct size doesnt fit because of the heater box and everything right there is in the way...

We tried a flexible tube but it won't sit at the right angle...

Anyone familiar with this issue? Anyone know the fix??? I have tried a tube for a big block dart, a different one, and a flexible one... Help!!!