You can use a Vishay TSOP 7000. It`s a 455 kHz IR eye and will work with your Beolink passive. It`s about 1 cm x 1 cm small.
Easier and cheaper than your solution. I don´t even know whether an LC2 will work.........I don`t think so.
Available here: http://www.lintronic.dk/InfraRedReceivers.htm - called TT-IR-1455
The IR range is not as good as the original Beo IR eye, but ok. You won`t have the direct volume control, just via Beo4.
Hope this helps.
Stefan