No luck with the pistons!
The low-comp SR20DET pistons I was planning on are no good after all
With the +12cc dish and 55cc head (+47,5 the head volume and +7.5 from the gasket, thus the compression ratio is 617:67, or 9.2:1, a bit too high for my taste. The dome is just 5.5mm thick, and the dish should need to be deepened by 1.5mm to achieve the 8.5:1 CR, leaving just 4mm on the dome. IE. no go.
There's two options left: full dome pistons machined to fit, or a custom set. Full domes will be quite expensive and the custom pistons will take a long taime to arrive (and are more expensive too). My choices here seem rather limited.