Engine An Odd Engine Question

If memory serves, I think the block was supposed to be left alone but the heads had to have a passage blocked to work with the Windsor block? It's been a while, but I was going to do the same thing 20+ years ago. Even spent the money and bought an actual Boss intake manifold.

I had picked up some Modified heads too, I seem to remember them being the same exact heads as the earlier 2V Clevelands but had huge combustion chambers in comparison. The Modified part of the name came from the blocks changing to accept a big block bell housing whereas the Cleveland accepted the small block bell. Since they used the 4V heads on the Boss 302 and didn't change the architecture of anything other than what it would take to accept a different bell housing, I would think that you most likely wouldn't have had to do anything to your block.

I do know, however, that the block will need a coolant hole drilled IF you were to go with Trick Flow heads. The earlier blocks didn't have a passage somewhere near the center(?) and a steam pocket would form which impeded or blocked flow. In those cases, you would use the head gasket as a template.

I don't know where you are with your build, but I'd double check the deck vs the head gasket. Worst case scenario (in my mind anyway...) is that you'll have a passageway that is already blocked that you'll need to drill.