Here is another tip for your headers. Most headers are not ground flat and true on the sealing surface so the bolts will never pull them down to seal. I always take my headers and true them up on a large belt sander. This gets all the contact surfaces in the same plane. With your six cylinder headers you may need to find someone with a four foot sander. They are common in cabinet shops, but cabinet makers are NOT real fond of sparks.
It can be done with a straight edge and a surface grinder, it just takes longer, but it is well worth it. I had a set of AMC headers that were so far out I ended up having to weld more material on the face to get a uniform sealing surface. Hope this helps.
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Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help.
RIP Bob Parks.
1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo
If it breaks I didn't want it in the first place
The WMB repair thread
http://67-72chevytrucks.com/vboard/s...d.php?t=698377