This is news. To me atleast. I have never seen anyone trying to simulate the !RD and !WR pins on other pins. Maybe you have special circumstances which force you to do so.

But I would tend to agree with the other posts which suggest you to use the two pins for the purpose they were intented and move the current assignment on them to some other normal pin.

Also I think, with the method proposed by you, it may not be possible to satisfy all the myraid timing issues associated with each read and write. Maybe you can achive it with lots of study and efforts - but it simply is not the worth the trouble.

Raghu