Gold and silver box EZKs are not necessary, they're only favoured because they can be chipped.
Here is a database of part numbers
http://www.nuceng.ca/bill/volvo/database/ecu.htm
I would just go on the Turbobricks forums and put up a wanted ad for an LH-2.4 ECU/EZK combo
The best ones would be the -937 or -954 ECU. I'm not sure about EZK part numbers, but ideally you would find someone with an ECU and EZK pulled from the same car. If you have trouble with the EZK I think you could do the rest of the work while you find one, as the car will run with the NA EZK, but it (I think) will have rod knock under boost. Maybe. LH-2.4 is fairly smart about that sort of thing.