Recommendations

Implement your GUI in the Screen Section.
To control the size and cost of your project, execute it in phases.
If suitable, allow a mix of character-based and GUI screens (that is, add new graphical screens and retain some of your existing text-mode screens).
Redesign your screens to make them less crowded and more consistent with the established look of the GUI environment.
Whenever possible, use the Acucorp workbench to design and prototype screens quickly.
Formulate a test plan and allocate time to execute it.