383 rebuild - kinda whimpy on the dyno?
Next;
A) did the chambers get relieved correctly for the 2.14's? Same as camelback Chebbys O/S valves are shrouded unless One does the proper chamber work. They can hurt flow...
B) I have found cyl's representing #3 & #6 to be shallow on a number of 906 castings, but just the same all chambers should be cc'd, and the indexing on the last crankpin may be suspec.........