I am not looking for a big CI SB. What I intend is (now that I've got me 406 with 3.75 stroke crank) using the 3.625 stroke crank when it comes time to freshen my 400 block(s) and they would be above the 406 we are restricted to. I'm spending an absolute mint on block machine work and don't want to have to get a new block everytime I need a re-build. But I am going to save for a motown cast block when it comes time to replace one of the 400s I have now.
As for GM 400s being junk, I've heard quite a bit that puts that argument on pause, for me at least. And I've decided not to fill my blocks, there are alot of downsides to that for oval track racing. I am, however, having the steam jackets blocked, on the advice of a machine shop doing some of my work.
I'm more than a little excited to see how the 393 does compared with the 406!