Mystery Component on CD32 Joypad Schematic

[Castellen]

It's just an RF suppression choke.  It provides a high impedance to RF signals (looking at the image, I'd estimate from around 50MHz upwards).

To cut a long story short, it isn't necessary for the circuit to work.  TL1 reduces emissions from the circuit above a certain frequency, and provides some immunity from RF radiated into the connecting cable from an external source.  From a design point of view, it seems strange why you'd include this into one of the external lines, but not the others.

I'd suggest not fitting TL1.  But it's usually good design practice to fit a 1nF (or whatever) ceramic capacitor between each external signal line and ground, close to where the cable enters the PCB.

[Castellen]

Or there's equivalent CMOS gates you can use (4000 series) which will do the same job.  They tend to have different pinouts, but nothing that 30 seconds with the datasheet can't resolve.
Either that, or do the same job using different logic.  You can just as easily use combinations of NAND or XOR gates to exactly the same job.  If you can't work it out in your head, then just write out the truth tables.

Regarding the inductor, the author hasn't even specified the type of ferrite to use (there are various different componds which react differently at different frequencies).  So the value of inductance vs frequency clearly is not important.  If you really want to put an inductor in there for whatever reason, just select any low current 100µH leaded inductor.  It's not going to make any difference.