It turns out that there are no .59 pistons (tolerance group #0 oversize) available from Porsche in the world. No warehouses, no dealerships, they are gone.
Sunset found 45 .69 pistons (tolerance group #1) in Germany. $288.62 and $43 airfreight. Not too bad. Manual says for first oversize group 1, piston is 100.490 + – .007 and bore is 100.510 + – .005
I should be able to start rebuilding it as early as end of September. Have to order rings, bearings and gasket kits once the block is done and pistons/rods are all balanced.
The cure for sadness:
1987 Porsche 928 S4 | Bring a Trailer