You really need to think about what you want. If you want a bandaid leave the motor in, buy a new piston and rings, hone it. If you want to fix the problem and be ready for more boost, like the 21 pounds you said you want to run, pull the motor, bore it, hone it, deck it, get oversized pistons and rings, get some eagle rods, new bearings, get the head resurfaced. So do you want a bandaid or do you want to fix the problem? If you've got access to this shop you might as well do it the right way.