Here is a link to some pics from the Chevelle Showdown 2000 in CT. July 7 to 9.
Yes- that gray 73 Chevelle is a 427 Motion Phase III L88. He has a lot of paperwork from Motion where the original owner was offered a special deal on using the last L88 Motion had vs. installing a LS6 or LS7.
http://hometown.aol.com/jjcczz/myhomepagephoto.html