I remember the 348/409 block was angle cut at the deck surface,one reason they had pistons that weighed as much as a smallblock crank. Seems to me,though,that GM used the basics of the W-block as a model for the first big block engines;their first prototypes used some of the W block internal parts and a modified 409 block casting.(this is from stuff I read in an article about the history of the bigblock Chevy in "Hot Rod" magazine several years back,so I might be a little off on details.)
