Douglas: While I would certainly look to the Sissell 12-port head for your project, you might just check out this web site just for grins:
www.falconerengines.com when there, click on the "hot rods" hilited text. If you haven't seen this, be prepared to be blown away!
Ryan Falconer has been around for years going back to the late 60s in CanAm racing. For several years now he has offered this incredible V12. What's interesting is that the specs for the engine are similar to the Chevy V8 in terms of many of the block and head dimensions. That's of interest because, like the small block V8, the 230, 250, and 292 Chevy inlines share some measurements like cylinder bore spacing at 4.40 inches (as I recall). So potentially, one of Falconer's V12 heads might be an interesting fit on top of a Chevy inline.
Obviously, fitting such a cross flow head is a significant undertaking with lots of block work, custom cam (the order of intake and exhaust values don't match), and how knows what else. But guys like Leo Santucci have assembled composite cross flow heads from sectioned small block V8 cores and they work really well.
Anyway, something interesting to look at and ponder ...
