OK; to really evaluate reusing those pistons, you need to really clean them, and measure them fully.
You need to make a sinkfull of simple green and hot water, 50/50, and soak them for about 10 minutes.
Scrub them with a nylon brush, or old toothbrush every 3 minutes or so.
Do not soak them over 15 minutes, max.
If you see them turning gray, remove them from the cleaning mix immediately; that's a phosphide coating forming.
You don't want that; it's rough.
After they're clean, rinse with warm water; you can scrub them with a toothbrush and baking soda to get the hard bits, but do not leave baking soda on the aluminum for more than seconds.
Don't get baking soda in the simplegreen bath.
After they're totally clean, you need to clean out the ring grooves, and inspect the ring lands, looking for cracks.
A broken ring makes a good tool for cleaning gunk out of the grooves; grind the edges so it doesn't gouge the piston.
Dye penetrant is a cool thing to do, but it's hard to do on a piston.
You want to know if there are cracks, because those bits might break off.
After they're totally clean, and have passed inspection for cracks, measure the pistons for wear, using either a set of calipers, or better, a micrometer.
You need to measure the piston and the bores.
Measure at the top, the ring spacings, and every 1/2" or so down the length, to look for barrel shapism.
This pic leaves out at least two spots I'd measure.
You also measure 4 places around the piston and bores; every 45 degrees from perpendicular to the pin, to inline with the pin. (inline with the pin will be missing some points, due to the cutouts for the pins.)
This shows the first two positions, the other side 45 and across the pin gets measured too.
The skirt is wider than the top; this is normal.
If it's barrel shaped, i.e. the skirt is narrower than the middle, then you need new pistons; they'll slap in the bores, wearing everything faster, and possibly breaking off the skirts. BTDT.
If the bore is barrel shaped, it needs to be bored; it won't seal well, regardless of new pistons.
IDK what size the SC pistons are, but there should be measurements in the manual.
If they're off by more than 0.002", you need new stuff. I'd reuse everything if it's within 0.002".
That's a lot of wear with these, at least as far as my V8 4.6's. everything there has been below 0.001" from stock.
You will also need to hone the cylinder a bit, and put a cross hatch on it so the rings seal.
I bought one of these: