Both block & head are somewhat different; other than the obvious difference of the oil fittings for the turbo, the turbo block does use dished pistons to lower the compression ratio. So putting that in a NA car would noticeably lower both performance & economy. The head is, I believe, an identical casting but it's my understanding that the exhaust valves on the turbos are sodium-filled for extra heat dissapation away from the seating surface (I know this was the case on the B21s, not sure with the B230s). And yes, the cam is different, but that's an easy swap as long as you've got some valve shims on hand. The heads are essentially interchangeable but the block would be an issue. I think the last year or two of the 240s used a B230F 'L' block with the oil sprayers below the pistons.
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Chris, Dartmouth NS Canada 70 M-B 280SE, 83 245DL, 84 244 turbo, 90 780 turbo, 92 VW Golf, 90 740 Rex/Regina