You could also use .040" over Olds 400 pistons. These are nearly the same dimensions as a 350 Pontiac piston at .035" over. You do not need to have the dish rim machined off to reach the correct compression height! Leaving it on will actually improve your resistance to detonation and will have the same effect as zero decking the block woithout increasing the compression. However, you will need to have the Pontiac valve relifs machined in. These pistons have the same wrist pin as the Pontiac.

I have a set of these pistons that I was going to build into a high-performance 350 project that I haven't gotten around to yet. The modifications are quite easy for a competent shop or machinist to make.