I have done a few of those big bore 396 cu inchers and I like them, but they were for higher rpm applications.
Still it looks to me that you are cooking good. Maybe you might think about increasing your rpm on the package if it will live and make additional power at the higher rpm. In some combinations the air pump spinning at higher rpm can equal and even overcome the bigger lower rpm air pumps.
Looks like you did good though with it.
Ed