Need to build a custom cable for Xilinx programming

I need to build a cable that will connect 15 signals between two PCB boards. This will allow me to program a Xilinx FPGA over the select map interface (clock, data rw, cs). Since these signals are all single ended and we have clock, I am concerned with signal integrity. In addition, one connector has Grounds while the other connector doesn't (actually going to span two connectors on the other side. I also do not have any termination on my clock. The clock rate will be in the MHz range. I was thinking of using a ribbon cable with modifications to do this. The connector without any grounds does have a couple of ground posts on the board I can attach to.



Both connectors are standard male .1" (.025 square post) connectors.

Any recommendations on how to connect this?

Thanks!