Originally Posted by jr's3800
The heads are also the same..
Just a quick correction..the heads are not "exactly" the same. The difference is two extra holes in the intake manifold flange that pass PCV to the intake manifold. You can add them to the N/A heads by carefully drilling them (use your SC heads and the gaskets as a reference to locate the holes.) This is one of those deals where GM used the same casting, but did a little different machine work to them. You don't have to be exact on the hole sizes, it'* just to route the crankcase blow-by into the PCV system. If your care full and start with a small drill bit, you can even do this with a hand drill.
The rest is true. The block and crank will interchange. The rods, pistons, and balancer should be changed to the */C specific parts....or run the N/A parts on a lower boost level (to compensate for the higher base compression of the N/A motor.)