Just did a bit more digging.
Looks like Ranfft says its a Slava 2427 auto twin barrel movement.
They confirm the button is the quick date set but I have yet to press it in case something pops out
Cheers.

Found a case gasket as you suggested for amphibian. 32/30mm perfect.
Now for a crown/stem gasket. I'll measure that tomorrow as my eyes are telling me to knock it off for today.

Thanks again for the guidance.