Need help putting in new electronic gauge cluster

[Sammy]

I have restored my '66 289 4-speed with an engine and components from a '95 mustang (302 5-speed), which has a computer. I am now installing a Hanneline 6-gauge electronic gauge cluster. Questions...What do I hook the Tach to (previous cluster had no tach). Also, The oil sending unit that came with the new gauges is supposed to replace the old one, but the old one is hooked up to the computer and I am afraid I may foul it up, how do I hook up the new oil sending unit? Lastly, same thing with the new water sending (temp gauge) unit, how do I hook up without messing up the computer?