Again, READ THE DAMNED DATA SHEET !

On using external memory P0, P2 no longer available. But I/O ports can be build as memory mapped I/O (with latches, tristate drivers).

If you use two 373 latched with ALE, it make no sense, both outputs are identical.

Again, memory mapped outputs should be build with /WR as latch signal and some address decoding (e.g. 74HC139).

At first you should write a memory map:
with address ranges are used for Flash, for SRAM and for memory mapped I/O.


Peter