someone asked me today about this, slightly shaving the intake side of the head deeper than exhaust side. what do you think?

 

It would probably create unnecessary turbulence and contriction when the air is entering the cylinder. If you are trying to acheive a venturi effect, there are other ways.

The valves should be seated at similar depths but they can have different angled valve seats to acheive that venturi effect.

 

That would make the head bolt bores not line up, as well as create an uneven mating surface for the head of the head bolt. It won't work.