Builders: Square engine, Over Square, or Under Square for you?
I have NOT read four pages of this thread. , so I don't know if this is for a n/a or power adder application.
But my answer for post #1...
I'd build a aftermarket iron block 400 small block chevy with sb2.2 heads.
Or,
a stroker crank to make 400 inches out of a Nascar dodge (R5,P7 ?)
And then spin either one to the moon.
Theoretically, a 396/402 with big chief heads could make some serious steam, too. Better would be a 4.5-4.6 block with a custom destroker crank to get to 400.