ease of implementation, optional features, etc.

[Drew Eckhardt <drew@kinglear.cs.Colorado.EDU>]

As far as design :

People are forgetting one thing : application notes.  Most vendors 
have application notes that give a working sample implementation using
their chip.  For instance, National Semi's AN-479 has full schematics,
a materials list, and a PAL program (for the PAL that does shared memory
arbiting and address decode) for an ISA 8390 board (AUI / thinnet, 
jumper selectable).  If you were to go with a shared memory 8390 
implementation you could take this design, and write a new PAL program....

In any case, the analog side (what scares the non-EE's among us)
with the pulse transformers, etc would allready be done for you.