Brand new reproduction water necks are available at $40 to $45 for the 67 and later style neck. They were originally straight during this time frame, no matter SB, BB, AC or whatever. Good used ones can be found as well, but will require some searching. They were cast aluminum and many of them will have massive pitting where the hose connects to the housing, which may be a source of potential leaks.
In regards to the plug wire holders at the thermostat housing, each series of engines, year model and body style can use a different style holder. You can modify or rig something up to work, but be aware that if your looking for correctness, then search out the correct style for your particular application. Todd Hoffman has reproduced most of the more common applications for the 63 to 79 year models and engine configurations.
For plug wires, there is basically only one company making the reproduction wires with the Mopar stenciling. These reproduction wires actually use some of the GM style ends / boots. As we all know, Chrysler would have two to three vendors for items, so on an original assembly line engine, you could find a possible mismatched set of wires on any given engine. Also, as slight modifications to tooling as molds or materials changed during the model years, you would see variances in the boots. It was not uncommon to see original engines with different date coded plug wires from the factory.
Finding a truly correct set of plug wires with the correct ends can take years to accomplish. Most of the ones that you will find are put together from multiple partial kits to make up one complete kit.
Thankfully, we have manufactures / vendors who have stepped up and reproduced these parts so that we can make the cars as correct as possible for 98% of the customers. Trying to make the parts 100% accurate could easily double or triple the pricing due to the different variations. For that 2% of the market, many of those owners will search out NOS or excellent used pieces.
