Could the BCU and existing feed assembly be replaced with a single or OMT Rx feed to use the dish for Rx?
Or would it require a change of the feed boom arm as well?
This assembly is different to the Ebay one as it has a C120 extender guide for a CM/Andrews feed. It's used with the feed shown minus the OMT and has a different adapter for the boom.
Looking carefully at this pic, from the listing, it has the Prodelin feed inc. OMT which has a WG17 input.
I guess that the Ebay one has a straight bit of WG17 guide in place of the C120 shown here. That would match the feed below. There's a flexible waveguide which I presume is attached to the opposite end of the WG17. The round bit on the OMT flange is not a C120 adapter but just a WG17 collar with angle markings.
I've not tried one of the Prodelin OMTs on RX but if it's got the bandwidth, you could probably fit one LNB inside the rotating cage and the other one the right angle port.