factory 72 340 pistons???

If you are milling the head you will need to mill the intake surfaces of the heads (best option) or mill the intake (worse option). It would be best if you could take the block, heads, head gaskets, and intake to machine shop and mock it all up before heads are assembled and have intake side of heads milled so intake fits correctly. Or do what I did and get it all together and find out the intake does not fit and mill the intake. Now no other intake will fit and the milled intake only fits your engine. Not the end of the world but spending some time up front would be best.