From Fallen London Wiki
Some napkin math for Shattered Mask source:
+2A per Contraption from zee dream +13A Print Paper +1A Assassin card =16 Actions
+ 59E in Journals
+ 10E in Broken Giant + 5E in Rostygold - 2.5E in Incendiary + 12.5E reward from Assassination = 84 E
84/16 = 5.25EPA
Pretty good, as long as you can passively get Contraptions while zailing. Plus you can still upconvert/sideconvert the journals for potential rat market shenanigans.