Hello Bill,
As you are aware, the 705C8A device contained only a few peripherals, and these had dedicated pins at the expense of a partial Port D. However, the more recent devices have many more peripherals that require to be multiplexed with GPIO pins.
For the more recent devices, you will find that most of the GPIO ports are only partially implemented, unless you use the highest pin count version (i.e. 64 pins). Then there is the additional problem that a needed peripheral will consume part of an otherwise complete port, as you have found.
I assume that you would prefer having complete GPIO ports in order to provide parallel byte access to an external peripheral, for example an external parallel RAM device. If so, I think you will have port allocation problems and may need to modify the approach, at the expense of more substantial changes to the existing code.
For the 705C8A, I presume you were using assembly code. If so, when migrating to a later device you will probably find it beneficial for the code to make much more use of the stack for temporary storage purposes, an option that was not available for the earlier MCU.
Regards,
Mac