I do not have a covan dash, however I have all autometer gauges and im sure the wiring is similar.
In general these aftermarket lights are very simple to wire. A black and a white wire, thats it. As easy as positive and negative. The new dash might help you eliminate any wiring problems in the old dash since you will have to find a power source for the new lights. Should be very easy. I would not lose any sleep over it.
Instead of having about 10-20 wires for the old dash you will now only need a positive and a negative to run all the new lights.
Heck I dont even have any of my original wiring for the interior lights at all and all my gauges work perfect.
I hope you are prepared for what Rita just turned into over the night. One of the largest hurricanes ever to enter the Gulf in history.
http://www.adfabdesign.com/Illusion/.../Interior.html