Not really sure what the problem is... One wire at s time, unplug (tag) from Impala and reconnect to same thing on ChevyII dash. You may have to change connectors...
On the dash side, I see it as easy. The problem could be if the 2 cars do not use similar sensors/senders..., such as fuel tank gauge, temp sensor...
This will take some time, but one wire at a time, it will easy...
