&gt24v

Hi, i am new here; I have a 1996 alfa spider V6 3.0 12V. i want to know if the engine 3.0 24V share the same block and other parts. I found a 3.0 24V engine, but with hi mileage, i just want to use upper part of the engine (heads, admission, eletronics) They will fit in the 12V block?