Leigh, I cannot offer any information about Lukens Pontiac but I did recall a discussion about dealer installed 428's from a while back. See: 1968 firebird with stock 428?????? . At that time, the only dealers mentioned that did 428 swaps were Royal Pontiac in Michigan and Myrtle Motors in New York.

So, there is a history of two dealers doing the swap on new Birds so it would be interesting to find a third one. Let us know if you locate any documentation on it.