Article on the car:

http://www.geocities.com/~lobird/428rt.html

I'm not at home now, else I'd scan in the photos for you. The issue was September 1968 Popular Hot Rodding.

Myrtle used 428 emblems on the hood, but left the 400 emblem on the trunk lid. I believe their reasoning behind this was that the trunk lid emblem signified that the car was a "Firebird 400" model (like a "GTO"), yet the hood emblems told you of the engine change. Either that, or they couldn't get a 428 emblem to fit on the trunk lid back in 1968.