I know you Kiwi's use a lot of Chinesium stuff since it's pretty inexpensive to ship to NZ. I don't know that those 440 Source pistons ARE from China but I would not be surprised. I'm actually surprised more Chinese 'performance' pistons don't show up here in the US.
I'm not a big fan of all that off shore stuff... good quality items are fine but so much comes over here that just won't meet my standards of fit and finish. My buddy just had a 440 done and he used some Chi-Com heads... visually they were fine but all the valves and springs looked pretty generic. His engine guy pulled a couple springs off to give them a quick look but never checked the machining or run out on the seats. Why spend $4,000 on a new build and cheapen out on the top end?
I have had my friends use Molnar rods and cranks that are off-shore but the difference is better macining and QC. One of my engine shops sez the same thing. If you are on a budget (like most of us) I'd look at Autotec/Ractec pistons... don't you guys have any NZ or AU suppliers down there?