i think i know what i did wrong. apparently there's 1 offset piston and i didn't realize it because they all looked the same diameter and side skirt length, but i just so happened to run into a subaru tech and was talking to him and he said that was likely the cause of not having compression at all in one cylinder.
the car still started up though, it was just running off of 3 cylinders.
and i didn't memorize the location of the shims, i had them in order but my friend rearranged them. 0.o