Cheap! Forged pistons are good for heavy boost. Not so great for a daily driver, but will do in a pinch.

Well sorry to drag this back from the dead, but I will be pulling the engine soon for the rebuild. Are all stock A15 pistons the same? I've decided to stick with the stock compression and just go with oversized pistons if the cylinders are damaged, but I'm not sure if the 210 pistons on rockauto are the same as what I have.

http://www.rockauto.com/catalog/moreinfo.php?pk=4807821&cc=1208832

If you wanted to source pistons with a 20mm gudgeon you could use CA18 rods (aftermarket forgies seem to be alright on price), alternatively some company was bushing them down to 19mm and marketing them as Datsun items on eBay a few months ago

CA16de rods are way strong, but a little it lighter than CA18 rods.
Personally, I would just race prep the stock rods, (polish, ARP bolts, balance, and shot peen) And run some nice forged pistons.
Standard pistons are weak, and will get puffy with boost use.