the plug spacing could certainly be done the way it is in the model if so desired. simply grind the cam to the correct opening sequence, use the correct rockers and move the plugs to the same side of the valve layout.
here are 5 small block chevy heads.
1.std. sbc wedge
2. sbc buick symmetrical port wedge
3. sbc symmetrical port splayed valve
4. sb2 mirror image
5. sbc hemi head
all these heads bolt to a sbc block. all use different intake and exhaust locations, valve angle and position (wegde, splayed ,hemi) layouts, rocker arm layouts, pushrods, cam shafts and spark plug locations.
everything your saying that doesn't work on your version of the v-12 could be changed to work for this design if so desired.