383 dart build

I don't think the manifolds will do your combo any favors. With the big heads and small cubes, it'll prolly want to buzz pretty high to make it's best power. I have a much milder 383 in my 67 Barracuda, .465" cam, iron factory heads, dual plane intake, (with a serious mechanical issue causing misfiring about 5,000 rpms). First trip to the track it ran 12.80, with a crappy launch. I expect once ironed out, mine will go low 12's/high 11's. I think you may want more gear and converter, and some headers. 11's seems reasonable to me for your combo.