having removed standard cast pistons from rods, and then fitted new 1s, i will be the 1st to say its a mare of a job lol

as said, needs supporting a lot, a punch or press the same size as the pin, plus a lot of heat from a blow torch!

obviously removing isnt a massive issue as if the skirt cracks, its scrap anyways, but refitting the new 1 needs to be perfection, and making sure the pin goes through the rod square, whilst its all red hot, its great fun

id go the route of buying a piston n rod complete on ebay, but if u want a standard piston on its own, i think 3 of my 4 old 1s survived intact, just stuffed up the loft destined to do nothing