273-4 spark plug question

Plug applications are just a starting guide, anyhow. The differences in "the same engine" AKA hi vs lo compression/ bigger/ smaller cam, etc would be generally colder for higher performance engines. And it "might be likely" that if the catalog say, say N10Y that up here in the N colder climates you might want to go 11, and in San Diego/ LA/ Tucson, etc, you might want to go with 9 "What came out" and do they look OK?