Well after spending hours cleaning all the pistons, I hear back from the machine shop that my cylinder bores are oval by 0.005", which means I need to oversize the pistons.
So it looks like new pistons will have to be ordered. I have two options: do a slight overbore and get an OEM replacement piston, or go big and bore to M3 spec, and get high compression pistons.
The machining costs are the same, so it comes down to piston costs. I think i'm going to go big - but my wallet isn't happy about it. I figure if I'm going to be putting in that much money, I might as well get some more power out of it!
The pistons I'm leaning towards are CP, with an 86.4mm bore, and 11.5:1 compression ratio. Should be fun to have an e36 330i track car
I also started cleaning out the interior a bit more - got rid of about another 5lbs of wiring, and started working on a seat template.