I think it's a '68 block.
I've never seen a lower pulley like this.

 

I have one of them also, I think mine was a70 or 71? Not sure why it is that way, it is just a cover. Also I think my engine was from a full size car.

 

Nope. Standard for '68, and possibly a couple of other years close to that.

I think it's a cool feature, and the original black paint is always well preserved under it, allowing you to get a good match if you want to.

- Eric

 

Oh! It's a cover. That makes sense.

Did 68 455's ever come with C heads?
This motor looks like its been together for a long time...only the paint tells me it was worked on at some point.

 

Yes, C heads were the ones used in '68. (Actually, without double-checking a reference, I believe they were used '67 through '69).

- Eric

 

Correct. Every single Olds big block made from 1967-1969 came with C heads except the 68-69 W-30, 68 H/Os without A/C, and all 69 H/Os. The latter got D heads.

Yes, I am saying that 68 H/Os with A/C came with C heads.