Well the EA bottom end is known for its durability and should be fine with relatively low boost, however, I would dare say that the cast pitons would probably be the weakest link in the bottom end. There are a fair few places around that sell HP pistons for the 3.9/4.0, Im pretty sure KB make some pretty decent slugs.
As for the manifold I think the only one you can buy comes in a kit, although if you have alook at "the market" on FF a member is looking to have a bunch of manifolds made up for a group purchase, im certainly looking into it.
Lets go find that Hotdog tree I planted
Lowered EF Futura
Black Steelies ( too cheap to buy proper mags )