I have a 1986 Olds Cutlass Supreme 307ci, .5L, 4bbl, automaticw/ac. I want to changeout the idiot light instrument panel to a Rallye Cluster with REAL instruments, and change all the sending units to be compatible with the Rallye Cluster.Is it necessary to modify or change the existing 14 pin plug, or can I just plug in the new panel, as is?