what heads are these?

[justin4260]

ok I've got a 400 small block with 2 different heads. I'm trying to find a place to get another one of this casting number 330545 and casting date d2 73. a guy i know told me he looked it up in a book and said it was a corvette head. i went t the auto parts store and they said they make reproduction heads but they don't search by the casting number they go by the vehivle and then they can chose valve sizes and what not. so i looked he head up and got 2 different sources saying different things. one place said it was from a 307/350 and another from a 350/400. well i know you can't put 350 heads on a 400 so I'm wondering why they worked even though its a 400 block unless they were 400 heads. any info would be great.
the first picture is the casting number
second picture is what outintheshop.com said
third is what nastyz28.com said