Yeah that was the document I was looking at. I guess it does list full side cover up thru '49. I've often wondered why the heads would not interchange. I know the 50-52 heads have 2 less head bolts, but it appears all the other bolts would align. If you put a newer head on the 50-52 block those 2 bolts would not really hurt anything if not used?? Though I'm not accounting for oiling on this, there may be differences in how the oil is carried to the rocker arms.
John