What is this? And should I buy it??

I'm very interested in this beauty but am uncertain what it is. The owner says it's a 1964 Dodge 440, but it looks more like a 1963 440 or 1963 Phoenix. It does have 440 side emblems and the dash emblem also says Dodge 440.
She runs well and has very little rust. The interior is in very good condition. It's been stored for the last 12 years or so. Has a slant six in it.
I'm going to check the cars tags and the owner's paperwork tomorrow, but I wanted to post here first. Owner thinks it's worth ~$10,000-$12,000...really???
Thanks in advance for any info!

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