Pistons?

[Volvoist]

I am looking for a set of pistons for my D24 NA. What brands should I be looking at? I figure KS and Mahle. I found KS but no Mahle. Who has the best deal on these? Are the rings that they come with any good? I am not sure what OS I will need on my engine yet. I have some pretty deep scoring on #2 as well as the normal cylinder wall wear. It was rebuilt once, but has STD size pistons/rings AFAIK. I am hoping the machine shop can tell me what size I need before I order so I can prevent ordering the wrong size. I was thinking of going to .040" OS to be safe, but really do not want to unless I have to. Advice needed!