High flow exhaust Manifolds?

I have a set of 340 manifolds on the 302 heads. You are going to have a clearance issue on the driver side. Due to the way the 340 manifold is designed it will hit the bottom of the head on the rear left side. You will need to do some grinding on the head to bring it down, otherwise you will have a gap and a constant exhaust leak. I used a remflex gasket to help but you still need to grind some of the head