So, after buying my 73 240z and putting in a new motor (the old one was beyond repair), I needed to figure out the hose routing from the thermostat housing to the intake manifold. The intake and carbs are from a 70 - 72 240z, but the outlet fitting was one from a 260z that had 2 of the 3 ports soldered shut. Instead of just getting a nipple fitting and a hose, I decided to do something a little different. This might help someone in a similar situation or if you convert to SU carbs and still have the Hitachi carb thermostat housing. I started off by finding the threads on the thermostat housing. They're 1/2" NPT. So I got a 1/2" NPT to -6AN adapter (PN: SUM-220649). For the intake fittings, they are 1/2" inverted flare (IF). So I got a 1/2-20 IF to -6AN adapter (PN: SUM-220668). Then, to connect them, I got a pair of -6AN to tube adapter fitting. After than, I got a piece of stainless steel tube in 3/8".
The tools needed are a tubing cutter, a tube bender, and a fine tip sharpy.
Here's the end result. As you can see, there's plenty of clearance for the distributor and plug wires. I started with a 90 degree fitting from the thermostat housing but it turned out that the angle is too extreme.
I hope this has been helpful. Any questions, feel free to ask.