Oldtruckspapa ,
Why do you think you need a new intake & exhaust manifold ?
Finding a GM NOS intake & exhaust manifold will be next to impossible to find .
I purchased a nos intake manifold back in 2008 .
I've only seen one other nos intake manifold that showed up on ebay in 2009 .
PIC
https://i.postimg.cc/7Z36f2XK/Copy-of-235-Intake-manifold-GM-NOS-3694163.jpgAfter keeping my eye out for a NOS exhaust manifold since 2007 .
One turned up on ebay last year . It's a super rare part in nos condition .
PIC
https://i.postimg.cc/HkwkNmCj/Exhaust-Manifold-2-3.jpg&
https://i.postimg.cc/mrVgSW-vM/Exhaust-Manifold-3.jpgBoth GM NOS manifold's had to carefully media blasted to clean off
light oxidation & light surface rust .
This is what I used in my blast cabinet .
PIC
https://i.postimg.cc/76WPpMYZ/Corn-Cob-blasting-Media.jpgGeorge
'54 3600