i think that the DOHC intake manifold for the X3 will fit.
ryanator (honk's old LC2) had an alloy manifold from an x3 grafted on to allow for boost pressures as the plastic ones were prone to cracking ! (according to Bretton and Andre from PSC)
from what i recall they used to source the manifolds, add a BBTB, clean them up and go from there.
i could be wrong but.
one of these i think
