Here's a bigger extract from the TSB I posted from above. Shows the header/title of the TSB along with the two sections that include all the "Truck Engine" options by model/series. The 327 was definitely available as an option for the 60 Series trucks, Looks like the 261 6 cylinder was the standard engine, with the 327 as an RPO.
Here's a link to a extensive
Chevy V8 Casting Codes listing that has a lot of info. Looking through that and fact checking on the web, I found 3 possible 1962 327 block casting codes:
3782870 - 1962-67 327 2 bolt main (not specified for any specific vehicle)
3789817 - 1962-67 327 2 bolt main Car & Truck applications
3959512 - 1962-67 327 2 bolt main service replacement block (will be stamped with the engine code suffix "CE" to identify as a service replacement engine)
