I'd pull the pan and check out the cylinders, and bearings. Then the head and change the valve seats. Other than that, at 40,000 miles, i'd expect to still see hone marks in the cylinder walls.

57 minutes ago, Muzez said:

since the engine is out, it should get a rebuild

Z engines are so easy to remove that this comment doesn't really have any weight.  Looks more like a guy with a business trying to get some business.  That's my first impression.  Mechanics need to mechanic.

As Mark M. says, inspect first, then decide.  I've noticed that the high quality parts seem less available today.  You could end up replacing good used parts with bad new parts.  If it's not broke don't try to fix it.

Thanks guys. That was my gut feel too. Will take a look first. May need your help deciphering what I am looking at first. 

Any tips on getting the EGR connector from exhaust to intake disconnected? Been dosing with CRC Freeze off and penetrating oil for a week. Tried heat but will try again. Is it possible to buy a new pipe if I need to cut it? 

@Mark MarasDid you mean valve seals earlier in your post? I think that’s what you were referencing. Try some Kano Kroil penetrant and MAF gas. A lot easier to work with it out of the car.

34 minutes ago, Yarb said:

@Mark MarasDid you mean valve seals earlier in your post? I think that’s what you were referencing. Try some Kano Kroil penetrant and MAF gas. A lot easier to work with it out of the car.

 I should have included valve seals but i meant changing the valve seats to prevent premature wear due to the lack of lead in today's fuel.

If you replace the head gasket it'd be a chance to pull the front cover off and check the timing chain and guides, tensioner too. Maybe a new water pump since they're available and not very much money. Check the rubber on the motor mounts in the engine bay. Those are fairly cheap too.

9 hours ago, Muzez said:

the car ran well and has only ~40k miles

This is the dilemma.  40,000 is not much.  The question would be, what has aged, not so much what has worn.  

On the valve seats, I think that they might have went to the harder seat material for 77.  I think it's in the 1976 Bulletin.  Maybe somewhere else.  Vague memory again...

 

Found it.  It's on page 8.

My n42 had bronze seats. The n47 on my 9/76 build date 1977 has steel seats.

Was it obvious by eye?  The color?  Never really looked at mine when I had the head off.

Yes you can see the difference in color. The old ones are darker.

 

Here's a good picture from @heyitsrama

 

 

Edited May 27, 20231 yr by siteunseen

My  early 75 California model had a N42 head, the gas gauge says to use unleaded fuel and the exhaust system has a cat. I wonder if the bronze would have been used on that head? was it generally known that unleaded fuel would be an issue?. should know soon since I pulled the engine with the intent of finding the cause of the excessive oil consumption.