The C9ZE... intake manifold is the correct numbered manifold for the 1969 S code cars.
Royce could say what kind of riser it is, definitely LoPo rather than HiPo.
There are so many unique and expensive parts to collect for a factory 1969 S code.
Heat shield, air cleaner base, air cleaner snorkel, lid, numbered Autolite carburetor, radiator fan and clutch, etc. this is a short list and it adds up to over $1500.