The real issue - although discontinuation is an issue - with the 82xx devices is that they are designed to match the x86 architecture, so they must be cluged into the '51 bus. To cluge them in you need a PLD (or a handful of discretes) so why not go all the way. The implementation of a memory-mapped controller for Andreas problem is very straightforward and can easily be done in the same PLD that handles memory-mapped I/O, ALE and the rest of the stuff. I have made many designs using 82xx devices in the early days of the '51 architecture and while a '65 truck may still run a new one is more comfortable. I do not advice against the 82xxx devices because they are old but because better solutions are available with devices that came along later.

Have fun, be comfortable

Erik