On the Bf 109 E-3/b, E-4/b and E-7 and the engine thingy. Do not distinguish the bomb carriers too much, especially not when talking about the engine. IIRC not a single E-3/b was produced (unsurprising since the E-3 went out of production even before the Luftwaffe even thought about using the 109 as Jabo) so any potential aircraft of that type would be converts. Although this is somewhat doubtful since they would most likely be upgraded to E-4 standards at the same time and labeled E-4/b afterwards, anyway.
IMO the E-4 (and E-4/b) would be the most probable candidates for the 601Aa while E-1 and E-3 should feature the 601A. IMO, of course.