The NCR8496 is a drop in replacement for the SN76496, as indicated on Technical Manual - Page 2 as shown in that link.
Okay, these chips really have way too much misinformation on the web...
But yea, the NCR8496 is indeed pin-compatible if it is a drop-in replacement (which makes sense... why build a clone when you don't make it a drop-in replacement?)... and the SN76494/SN76496 manual specifically says they can be used as a replacement for the SN76489A:
http://www.datasheetarchive.com/dl/5751294a53453c93311ad2e2e9a868e4dd7779/O/SN76496
What that manual seems to say however is that the 94-variation has the divide-by-8 removed, so it needs a ~500kHz clock signal, where the 96-variation has the divide-by-8, so it takes a ~4 MHz signal, like the 89.
So that means the 96 is the one you can use as a drop-in replacement, and the 94 you could use, but only if you add an external divide-by-8 circuit on the clock.
The manual doesn't make it clear what the difference is between the 'A' and the regular version of these chips though.
At any rate, I think my list of possible chips so far would be:
SN76489AN
SN76496(A)N (I have not seen any pictures of the 'A' version online. Might be rare)
NCR8496
There may be others that are interchangeable (like the 'A' and non-'A' versions, but no conclusive info yet on what it actually means. It could be that inverted signal that Wiki says, but why isn't that mentioned in the manual then?).