The NisMo heads are raw casting with minimal machine work done. They need complete port shaping, seat/guide machining and installation, and require custom manifolds due to the different port locations. They have a completely different valvetrain(rockers, pushrods, manual lash adjustment, etc) as well.
The heads are available from NisMo for $750 per bare casting. You purchase the rockers, lifter cups, pushrods, flanges, etc. separately from the heads.
To make these heads worthwhile you will have to pay a competent nissan engine builder lots of money to build them. A rough guesstimate of cost(not including the cost of the heads and valvetrain parts from Nissan) would be around $4000. You could spend less on them, but then you would not be getting the full benefit from them, so why even spend the money in the first place?
The bare heads as they come from NisMo. Note the pushrods, cups,
rockers, and exhaust port flange(to make manifolds). Note raw
ports, not valve seats/guides, etc.
View into bowls. Note manual lash adjustment on rocker arm.
A raw casting Electramotive made to make custom intake manifolds.
Note coolant manifold is separate from manifold as much as possible
to reduce heat transfer into manifold.
