There isn't a 1" rule that I'm aware of. That's in the IT ruleset regarding port matching.
Its not very hard to actually look up the rule, instead of speculating. From the GCR, the nasa rule is identical:
1. 1.6L (1990-1993): The exhaust manifold internal factory welds may be ground from the inte-
rior of the OEM exhaust manifold up to 1” from the mounting surfaces of the cylinder head and
A bead of weld or braze may be added to the outside of the exhaust manifold
inlet and outlet mounting flanges for the purposes of repair only. No coatings are permitted on
the exterior or interior of the manifold. Heat wraps may not be used.