Assuming the dyno numbers are correct and that the engine is working properly then I'd say your port size is too small. If the ports are the correct size for that engine then it should make a lot more power. The headers are big enough and so is the cam and a tunnel ram should support the power so that leaves the ports as the likely problem. But before jumped all the way to that conclusion I'd check everything over while the engine is on the dyno. Do all plugs look good? Are the EGTs fairly even? Did you check intake vacuum at WOT? Double check firing order? Run a compression check, a leak down, etc.? There are so many ways that engines can get messed up on the dyno you could write a book about it.

Were you really running 9 inches of vacuum at WOT? That is probably a bad number but if it is real then that would be an issue.