18" rad with e-fan has less clearance than the 24" with e-fan between fan and water pump -> If you put an e-fan on a non-AC turbo car and compare it to a AC turbo car, yes. Swapping to a AC model radiator, intercooler and pipes as well woud give more clearance.
The radiator thickness seems to be about the same, but there's difference in the brackets: NA non-AC, NA AC and turbos with AC use short brackets for the radiator, while non-AC turbos use long brackets (for both the IC and radiator). I'm not sure if the short turbo rad brackets are the same as the NA ones since I haven't had a turbo car with AC. Pictures of older 740s seem to indicate there might be some differences in the lock plates as well.
Here's a couple of pics from do88s site to demonstrate the difference:
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