Building 69 383 for my 69 dart.

If you want stock look and those power figures, you'll need more than 383". I would suggest a stroker package. A 496 with Stealths or well-ported factory iron will reach those numbers easily, and be able to run the number looking stock. You can search this forum for 496 builds.
That's what I'm starting to think without a SC. Might be a waste of time to go to 383 and be slightly bigger than 360. Might as well throw a 440 in