You've probably noticed that EPROMs and SRAMs have similar pinout in many cases. There's nothing to prevent you from using FLASH memory nor is there anything to prevent you from using SRAM + MCU + CF (or any other form of MCU-accessible storage).

Now, for starters, I'd certainly consider using the NMOS EPROMs that I've offered you. They offer only a 1:1 replacement, though. With a FLASH memory, you can store multiple EPROMs' worth of data and simply "add" an offset to the address to make it "look" like the EPROM you can't find.

A CF module requires that you "talk" to the CF in a specific way and that you subsequently emulate the EPROM. The easiest emulation, IMHO, is an SRAM. An MCU can do the "heavy lifting" and can transfer the data to the SRAM. If your hardware simply uses only 4KB of the SRAM, it's pretty easy to do.

A CPLD can also do the job, but it's more difficult if you are unfamiliar with the associated techniques. I simply thought of the CPLD as an easy way to reduce the physical size and complexity of the circuit that you have to build. If you have to change the logic, it's easier to do it inside the CPLD than to change your board, even if it's hand-wired.

RE