Thanks guys for all the input! Especially being not Scott related…
Some persistent googleling (is that a word?) showed that cast iron pistons are still in use today in air brake compressors for trucks etc.! Like this one:
Of course a compressor piston has a somewhat other purpose than a combustion engine piston but they sure look the same. And a compressor piston will get pretty hot too I guess.
I have contacted a few manufacturers for more info. I will post the follow up here later.
Maybe I make a mistake in thinking a compressor piston could also work in my Premier engine. If so, please tell me!