I've got a fairly built motor as well, granted that it didn't make as much power (N/A 331). Sounds pretty awesome as it sits with BBK short tubes, bassani header back, I'm sure it's going to be rad with a good set of long tube headers.
It will sound very different with long tubes, especially if you increase the primary size. Going from 1 5/8 shorties to 1 3/4" long tubes made a audible difference in my setup. The CNC port work and better intake probably helped as well.