no you cannot they are not interchangeable the 89 heads are fuel injected heads and the 79 are carb heads and will not interchange
yes
Yes. they didnt change the 350 block very much.
sure can.
No. The 350 has bigger valves. While you CAN put the 305 heads on the 350, (I can't imagine why you would actually want to) you can NOT put the 350 heads on the 305. Because of the 305's small bore, the valves on the 350 heads will hit the cylinder block.
No.
the heads should fit as long as your not trying to put them on a big block
yes just get head gaskets for the 350 not the 327
You can put Oldsmobile 350 heads on an Oldsmobile 307, if the 307 is 1984 or older. It will take some work but it can be done, I know for a fact that it can, because my 307 has 350 heads on it. It runs great. I'm not sure about the cam though.
some heads are vis versa
Yes you can
noNEW ANSWER: Sorry but the above answer is wrong. The only thing that is different on the 400 heads is that they have steam holes in them and it don't matter if they are blocked off by the head gasket. And YES they will bolt right on the 350 block with no problems.