i think he may struggle to find aftermarket pistons tbh thats the thing, ive not looked into them much
but from what ive found so far not one of my suppliers stock piston rings and i have a lot of suppliers too, i know i could probably pick some up from maybe gmc cituning like you say, but going fom that i htink aftermarket pistons wont be easy to come by
i know they ent cheap though lol its a bit of a shitter, but this is where it helps having a good mate work for citroen too

i get some mega discounts so i wont be paying much more than an aftermarket set tbh and best ive seen having a breif lo was hiflow heads at 90odd quid plus post, so i dont mind paying the tiny bit extra lol plus for how much i paid for the rest of my stuff for the engine build, it makes it even better lol