Has anyone taken a look at using one of Ryan Falconer's V-12 aluminum (cross flow) heads - presumably the "driver's side" unit to align the valve train up to the Chevy I6 block layout? If I recall the article I read about them, his V-12 block is based on a 4.40 cylinder bore spacing (as used by the SBC V8) so I believe the head would align with the I6 in that respect. I'm sure one of these heads would NOT be cheap (and Falconer may not part with a single head at any price) but using it would at least eliminate the head fabrication part of the project, and therefore some of the problems others in this post have pointed out. I'm assuming all the block work (fasteners, water ports, and closing in the valve train where necessary) would be pretty much the same as is needed for a composit (hybred) head. If there is any interest, you can take a look at Falconer's web site. Perhaps the folks at Falconer would part with a head gasket (for a price) to help assess the various alignment issues? Just a thought . . .