Here's a place I go to to see what parts might be correct.  Found a 75 there, with EGR.  Like yours.  No AC though so the AC vacuum ports are blocked.

https://bringatrailer.com/listing/1975-datsun-280z-43/

 

hah, I'm excited and bummed at the same time.  Since I don't know a lot about this car, I was hoping for a good original car to have as a baseline and then slowly work my way up as a learn more about what makes it tick, but I'm pretty decent at problem solving once I have a good working knowledge. 

All this chat has me really motivated to work on it more, and I really appreciate you guys with your conversation and information.  Its been a long time since I have found a good forum to socialize.  I'm looking forward to learning more and hopefully I can eventually contribute to the community.

I got my P90 head down and took some pictures.

Zed Head it was right there before ours eyes but I didn't see it because I didn't think the N47 had one yet, but I was wrong.

Here's his N47 head with a hole in the passenger's side just like the P90.

My '77 N47 doesn't have this. Must be a ZX thing? And the Maxima head is a MN47.

 

Edited February 7Feb 7 by siteunseen

People call it the "M"N47 because it comes from a Maxima.  But there's no M in the casting number.  

Edited February 7Feb 7 by Zed Head
Having a bad run of errors!!!

12 minutes ago, Zed Head said:

People call it the "M"N47 because it comes from a Maxima.  But there's no N in the casting number.  

You're right as usual. There is an N but no M in the casting number. More coffee.

@nowak1981 you have a hard to find cylinder head, don't get rid of it.

So I had a thought.  Look at the picture with the block number.  Is that an original paint color?  See how it oversprayed onto the head?  If it’s a factory color, I don’t think the head has been replaced. Even the rust bubble line up a bit.

You have a Maxima N47 cylinder head on top of an L28 block. Maxima's had 2.4 liter blocks which would be stamped L24. A Maxima head on a L28 block raises the compression and runs better. 

I would guess you have the original block from 1975 which would be an N42 with dished pistons. 

That is not the head that came on that L28 block but you do have the parts for a good running car. 

Clean it out and get familiar with the car before worrying about the motor. You have a lot of reading to do. And to be clear, do not try and start the motor as it sits, in fact take the battery out of the car while you're working on getting things figured out. Running the fuel pump would be terrible this early.

 

 

 

I went and got some ATF to pour down the cylinders

then I’m gonna drain and remove the fuel tank and likely go get it cleaned.  I’ll also unbolt the exhaust manifold to see what the runners look like and put it back on.
Then  I’ll pop the valve cover off and take a look.  

my plan is to remove as little as possible and then put it back together so I dont forget stuff and just creep my way through it.  The cold snap is coming through so it’s gonna be a little bit before I can get back out there.  
 

I also need to put up some lighting and figure out how to clean/blow out any hard fuel lines.  I can’t have an air compressor,  hopefully real estate starts picking up and I can find house.
 

 

Since you now know that the head has been off and your hopes for an original engine are gone I would change direction and take time to verify that whoever swapped heads did a good job.  Check valve lash and timing chain wear.  

1975 has the engine serial number on the ID tag in the engine bay.  Compare numbers to see if you got just a head swap or a complete engine swap.

The tag is over by the brake master cylinder.

Original Nissan parts have a notch on the timing chain sprocket that will indicate wear.  Rotate the engine to the zero on the damper pulley timing mark and make sure the driver's side of the chain is tight.

54 minutes ago, nowak1981 said:

also need to put up some lighting and figure out how to clean/blow out any hard fuel lines.

I like to use piece of unjacketed aircraft cable for this, maybe 1/8" or 3/16". Put a lot of carb cleaner down the line. Let it sit for a while and then feed the cable in. Chuck it up in a cordless drill and spin to help brush out the inside of the line. When I can feed it end to end with out interference, it's good. You could get a compressed air tank and air it up inside your place. Then use it to blow out the lines.

30 minutes ago, Patcon said:

unjacketed aircraft cable

 Can this be found at Home Depot? 

Careful with those exhaust bolts especially the one on the rear of the engine that mounts the hoist harness plate. You can snap a stud in a heart beat. Soak them thoroughly for a couple of days before attempting to remove the nuts.