Even though he has a good bit of color, by definition he is NOT pastel. To be a pastel he would need to have much less melanin (black) than he presents with. However, when bred to a pastel he would make some awesome babies because of all his underlying color. A good place for you to read up on what a pastel really is would be on Jeff Ronne's forum. Jeff was the first to selectively breed for and define the pastel trait in boas. Briefly, the pastel trait is defined as a reduction in black, not necessarily the presence of color. If you go to theboaforum.com you should be able to find all the info that you need.
Hope this helps!
Denny 