I was pleased to see you were building a project that uses a type 192 board.
These as you know are as rare as hen's teeth, Unless you've done your homework you would not be aware that this connects via two leads directly with the A1134A INTERCOM unit on aircraft like the Avro Lancaster.
Please can you send me details of your build. And how far along you are now in 2013?
Sadly if you REALLY want an item you have to pay the going rate to complete your RAF collection.
In my own case I waited 50 years to get my hands on a RAF T1083 Transmitter!!!
Dave what kind of lanc wireless set up have you got? Only ask as I've got a harwell box replica. Just keep on keeping an eye out for the plug board, I found one and a few intercom amps a few yrs back only £20.