saturn heads

will the dohc head fit or bolt up on the sohc block or are they the same block just different heads if so i dont have to buy a whole engine just the computer right ?

I'm pretty sure the heads are interchangeable but I thought I read somewhere that it's better just to swap in a complete DOHC long block. Just make sure you get one with the proper EGR valve mount for your year and later Saturns use one coolant temp sensor for gauge and PCM while earlier use two. 91 and 92 engines have a different crank tone wheel and are not compatible with later cars.