PDP-8/11 bus interfacing ICs

I've just got some prototyping boards from Douglas Electronics that I'm planning on using to build some prototype cards for my -8s and -11s. My intentions are to develop an interface to a PC to implement some virtual storage devices. If all goes well I'd like produce these cards in small volumes and so I'm keen to use off the shelf components as far as possible. The main problem of course is the bus receivers and drivers as these are pretty much unobtainable as far as I can tell. I'd therefore like to find suitable alternatives. Does anyone have any suggestions of suitable devices? Examples of chips I'm looking to replace are the DEC 8881 driver, DEC 8640 (or DEC 380) receiver. Thanks, Toby -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.