You can read that ad and tell he is full of crap.
For one thing a cam that has .620 lift with 1.5 rockers would have .661 lift with 1.6 rockers.
Guessing the horsepower based on a magazine article that used different cam and different heads......LMAO!!
I'm sorry you got screwed maybe Scorp will shed some light on your options besides your foot up his butt.
Caveat Emptor