Thanks for the help!

I am puzzled as to why you would have had oiling problems with that head interchange, I have swapped early 70's head on a 79 528i and 80 or so on a 71 2800 and several others that are closer and I have parts catalogs that list the same head for everything except the 82-84 3.3. The valves are the same thru the M30b34, the later b35 uses bigger valves. As far as cranks go, if you have a block with bubbles or bulges on the side down towards the bottom of the block you can use a longer throw crank, the 3.3,3.5 or 86MM throw crank. I don't think the 2.8 block will accept the long throw crank without machine work, but I am not sure. The bubble blocks started about 77 or 78 on the 530i's, also, those were probably the blocks marked 3.0/3.3. You can bore out a 3.0/3.3 to use 3.5 pistons, I have done it, but it is expensive and good machinists can be wary that you can take out the block that far, it gets thin but I currently have about 70k on that engine so it does last. The old US 2500 was 86 bore by 71.6 stroke. (I think) And I believe the intake runners are all the same, not right or left, except for the cast in boss for the bolt hole to hold wiring or a fuel line etc.
Hope this helps,
Mike W.