IBM 3278 term needs keyboard

My insatiable terminal collecting habit has cost me another couple square feet of space. By way of a well-spotted Craigslist ad, I have acquired an IBM 3278-5 terminal: https://picasaweb.google.com/102190732096693814506/IBM3278Terminal I'll need a terminal controller, so it'll be a long time before this term sees a mainframe session again. But it does power up and I'd like to at least test the local mode, so I'll need a keyboard, too. A few have appeared on eBay recently and sold for much more than I expected. Apparently there are a lot of 'boardless terminals out there. Aside from waiting patiently for one to come along cheap, what are my options here? The keyboard connector is a 25 pin and I believe it uses a serial protocol. Are there other IBM keyboards that may work? Any that can be adapted? For terminals, I have a 3178 keyboard (p/n 6052141) with the 15-pin connector. I know there is a 3278 -> PS/2 adapter project out there but it was intended to go the other direction, to use the 3278 keyboard on a PC. Perhaps it can be adapted to go my way?