Yes I'm running brass nuts on my k5 with stock log manifolds since ~11 years. I had to retighten them after the first heat cycle and never touched them again.
The brass nuts come with dorman exhaust manifold stud kits.
I have 2 hookers at home and my wife likes 'em too :D.
They are well made, nice casting and the machined surfaces are very smooth.
I ordered the blank version and painted them with high temp paint (1472°)
Not installed yet, I will post an update how it fits my 74 C20 gen1 350.
I think they printed just one instruction sheet for all their master cylinders and add the red sticker for master cylinders that should not be bench bled.
I would follow the instructions on the sticker.
I guess I'm lucky, I'm running summit brand brass prop valves in all our vehicles with no leaks and they work as expected. They are in use since 10, 7 and 5 years, maybe the quality was better back then.
I just received my distributor advance tuning kit and will start adjusting the curve on my K5 for my needs which is mostly cruising. I have a avs2 on it which is tuned for my needs but will go over it again as soon as I'm happy with the distributor.
@Ricko1966 Thanks that you brought to my...
I have Classic parts door handles for my C20 and LMC for my K5. They are fine and look exactly the same, I think they are produced by one manufacturer.