Slant build / pistons

ok, so I'm finally going to build a slant. Have wanted to and started once before but, life got in the way. I have a ported head with oversized valves, performance cam( don't remember the spec's ),hurricane intake, header. Now the questions begin. I have a later cast crank block ( milled .120 ) with stock pistons and new rings in old bores with a quick hone job. The ring gaps are way over the standard .004 per inch of bore. Do I tear it apart, bore it and run it? What pistons do I use? Is it worth buying th longer rods and forged pistons? Or do I look for a short block? Would really like some pep out of it. It's going to be my summer cruiser and might see a supercharger down the road ( 5-10 psi max ).