The requirements you have specified sound like a great application for our FlexRIO Products which are available in either PXI or PXI Express form factors. This product line has an onboard FPGA where you can implement the custom logic that you need for processing the data. In addition to the FlexRIO module you will need the Adapter Module (FAM) that will turn your module into a digitizer. It looks like the closest FAM we provide that is similar to your current specs is the NI 5732 which is a 14-bit 80MS/s digitizer but we also have better modules available.
Anthony F. Product Marketing Engineer National Instruments