It's looking like the hardware for this could be had for fairly little money. ICs are looking like $250-$400 used, water pumps are ~$200 new, and the heat exchanger looks like it's $300ish new. Make your own lines, fittings, and charge piping, and you're maybe $1000-1200 deep. Then sell your old parts and get $400-600 back. Doesn't seem to bad to me.
So, who has any idea how the water pump is going to be controlled though? Is the S55 pump table driven in the DME? Could this be a simple add, or a simple wire splice to run the pump based off of engine speed, fuel pump duty cycle, or map reading?