I've decided to take account of the various suggestions and make my board as general-purpose as possible. It'll have the bare minimum on it, and consist of a small plug-in module (four-layer PCB), for use with a motherboard which will have the ADC mounted on it, and a socket for the SR V5. The motherboard may even be home-made, for prototyping, and for use with another ADC or radio front-end. I designed something like this a few years ago, with an Altera Flex 10K chip on it. It had a 64-way DIN41612 connector on it, to which I attached prototyping cards with things like a VGA interface, LED displays and pushbuttons. I even implemented a very simple CPU on it, based on one written in VHDL in Hamblen and Furman's book: Rapid Prototyping of Digital Systems. I did something similar with a Xilinx Spartan chip.