Well let's see......... George Linder built the 77 Challenger and my company built the 81, which is technically a Shadow, not a Challenger.
In 1981 we built two "stepped" hulls. To my knowledge, these were the first "stepped" production fibreglass hulls (based on antiquated seaplane pontoon technology...that we didn't invent). Of course Reggie "invented" steps later ..at about the same time that Hustler "invented" them.
One was a stern drive with a turbocharged 260 Mercruiser. The second was an outboard .......... They were both grey and navy blue originally and were displayed at the New York Boat Show. The steps were approximately 4 feet ahead of the transom and were 1 1/2" deep. The performance was similar in speed but both boats were "slippery" in turns and did not track as true as the standard bottoms. I remember suggesting to the eventual owner of the outboard hull that he "aerate" the steps by drilling holes and running an air manifold from a scoop on the deck or hull sides. I also suggested small aluminum fins on the outer strakes and chine to "lock in" the stern. (Something you Stepped bottom owners might consider.....
Based on your question I guess he did some of that...... The boat had a single 225 Mercury on it at the time.
Enjoy it....them,...and come to Skaterfest.....George and I will both be there.