What the heck! Any ideas on how to fix previous owner's creative solution?

Sure! I believe they are just NPT fittings. Just get a straight and a 90 NPT 5/8 barbed hose adapter from Home Depot or a parts joint.
Nick

Thanks for the replies. NPT is a US standard (inches), where I would think the Datsun motor is metric based. Its sounds like there is a thread pitch close enough and the brass is soft enough to seal. Thanks.

280Z-hab Quick question?. Just for my clarification. So your not supposed to connect a hose between your blocked off water outlet pipe to the outlet at the rear of the head?.

Read back to the post form Tony D not long ago and there will be your answer.

hint: if you can't do that, the answer is no do not loop the water outlet pipe to the outlet at the rear of the head. Just block them off with a plug of some sort.

Thanks Torquemonster... I have turned the napalm valve back off and will now march to the next post...

HealyZ---that 10mm line (or 8mm) is a bypass around the thermostat back to the pump inlet, this compliments another passage in the right front of the block that does the same thing. These are there to prevent cavitation of hte pump should some moron rev the heck out of the engine before the thermostat is cracked open. If your engine is not overheating, and you plan on running a heater, leave that small line in place as it helps the car warm up faster. It also, as stated, allows circulation within the block while the thermostat is closed. That is a good thing.

For ultimate performance and heat removal these lines and internal passages would be attended to in some manner...a manner in which I'm not inclined to discuss at this point.

Tony D, You're the man. It makes sense to have these small lines in place. I looked through the FSM and did not see a diagram on where these are routed. Anyone have a picture or could explain where these small lines go?

Thanks Torquemonster and Tony D for the clarification.

Tony D, Thanks for not lighting the Napalm. I would not have had enough time to apply the SunBlock.

Healy Z, I'm REALLY swamped at work now and will likely be working late.
Go to Cardomain and look under username Sharkie73Z, there should be a red 260ZT project. There are 10 or 14 pages on that site, one of these pages shows where the little bypass hose goes---in short from the lower thermostat housing to the pump inlet where you have the yellow line. The webpage shows the line and etc.