The clearances are usually made on the pistons to fit a certain size overbore, example the forged Icon piston from KB would be around 4.4440 to 4.4460 for a 4.350 bore while the same size hypereutectic might be from 4.4978 to 4.4980
They would both have the proper clearances that KB would want for that size bore
On your deal I would order a set of pistons and rods and measure them before deciding to keep and use them, if they clearances are to much send them back and go to the next size over bore
BTW, you can order a custom set of pistons in any size you want, IE, for 4.4530 to 4.4590 instead of going to 4.460