I'm just saying..
I was curious about using aftermarket pistons in a 4/6, So I grabbed a 4/6 jug and tried some aftermarket pistons. I tried three, I think they were all SPI pistons. Two of them would have worked and one the ring gaps would have been going over a port.
Based on that, some aftermarket pistons would work and some won't.
Just putting that out there.
Lloyd