I have that issue, great Corvette stuff in there. I expect that Mad Mike will be posting the Corvette articles on
http://www.motionperformance.com soon. I scanned them for him a while ago. The best reference that I have seen on these cars is the original sales material contained in a book called Chevrolet, The Performance Years by Martyn Schorr. You can probably find a copy on Ebay. This material does show several engine options availavble in addition to the Phase three package. It is also mentioned that the "Competition only" (L88) type engines or those fitted with internal modifications were not warranteed. One thing That I have learned from collecting these magazines is that it is not good to take what is in each individual article as ironclad fact. The articles can often contradict each other or just give information that I now know to be inaccurate as to factory options and other issues. I have not seen other refrences for the Stage 1-6 name for the engines. The picture that emerged for me after reading all that I could find about these cars is that you could have had anything that you wanted on one of those cars, if you had the money.