Used to be a desired colour,special order only.
http://cgi.ebay.com/ebaymotors/Cadillac-Eldorado-1969-Cadillac-Eldorado-/230666117574?pt=US_Cars_Trucks&hash=item35b4c5a1c6
looks like a standard point distributor not an HEI as he says in the add. might be other bullshittery going on to.
Definitely not GM HEI. Big yellow coil wire.
Maybe a conversion to Pertronix or similar.