W2 head porting observations help needed!

Now, ACTUAL flow numbers aside, I have noticed quite a few interesting differences in this set of early W2s, and the later set that are mine. The early set has that rounded short turn shape, where the later ones are flatter, the early ones have a big square guide boss, later ones are much smaller, the early ones have a hump in the exhaust port roof, later ones do not, and interestingly, there is almost NO pushrod hole bulge, or headbolt bulge in the early ones, but quite noticeable on the later ones.