What is the intended purpose of this engine? Just to beat your brother, street, strip, what? What type of fuel?
Some more thought needs to go into this build. Really, what's the budget?
What does it mean "machine the pistons -.010". Your combination with 906 heads will yield 9.4-9.9:1 compression (depending upon deck height and gasket thickness) which is not a bad idea but it won't want a big cam.
Nothing wrong with them, but why the 906 heads and the 6-pack carburetion?