deck the block vs aftermarket pistons..

I have a 77 318 that's 8.5 to 1 cr ill be adding a set of 302 heads with 188-160 valves but would like to be in the barpark of 10 to 1 cr so what would be better to do deck the block or Aftermarket pistons...

If I deck the block how much would it cost and how would I know how much to take off, what else changes when decking the block other than pushrod length..

I know I can get kb pistons but that's around 300$

Over all I'm looking for more HP when I throw the 302 heads on and what is zero decking anyway? Thanks