Thanks Curt,
Are you referring to the 3 bosses on a triangular pattern?
I went back to some pictures of that engine in the '58 and I saw white dirt dobber holes meaning to me, they are tapped.
I was curious about the tapped bosses though and went back to view the pictures of my 261 build for my '59. Those bosses are also tapped.
I went to a website and printed off a sheet of casting numbers for Chevys to take with me when I visit that '58 again this evening.
I'll come back and report the results... fingers crossed!
Jerry
