Its hard to see how you can get there with parts you have. As you said, milling the block won't help. What is the CR as it is now? If its around 9-9.5:1 it would run fine on pump premium. I'd consider running it as is. To get quench you would need quench pad pistons fitted to the heads (KB hyper's?) or a head with flat quench surface.

A Magnum type head may be a good option to work with your pistons. With a thin gasket and/or some block milling you would get your quench.