I'm rebuilding my 80" evo and replacing the pistons with 9.6:1 keith black .020 semi domed pistons as they don't make 9.6 flat tops. These domed pistons shouldn't cause a problem with the stock heads right?

 

Check with Keith Black! It depends entirely what heads those pistons are intended for. However if you mean KB920 pistons (I'm not sure that is the same firm as Keith Black) they look fine to me. The 'dome' is hardly noticeable.

You need a suitable shop to rebore your cylinders correctly and they should be able to advise you. The stock pistons are fairly flat, so by definition to increase CR your new pistons will have to be slightly domed, not flat. Ain't no way out of that!