First, welcome to CHR! Glad you're here. NastyZ28 is about the best place to find SBC casting number info - Small Block Chevy Cylinder Head Indentification Looks like you're on target, and that the heads were an item '62-'67. With those small valves I'd ditch them for something better, ideally aluminum for better heat dissipation allowing a tad more compression.

Just a few days ago Glenn posted his suggested build for a 383, starting with a bare block. It's got a ton of good advice, if you're set on building your engine vs buying a complete package, link here -
Changing compression ona built motor