You mentioned a cast crank, I thought all 273's had forged cranks. The ports are much bigger on the cast iron 34o intake than the 273 heads. Thanks Webby.
I figured the intake would have to be port matched. From what I found the early 65-67 273's were forged crank. The later 68-69 were cast. Mine is a 68 so I got the cast version.
