Is there a site that I can go to and look up the block and head casting numbers? I would like to know what I am purchasing. The block # is 10066036 & the heads are 83417369. Any help would be greatly appreciated.

 

Mortec.com Do a search for this kind of thing. I've found at least a dozen places where this question has been answered. Your looking at a mexican made 350 motor that goodwrench sells as a crate motor. Those heads are a mystery to me. Maybe aftermarket?

 

On the heads he says that it also has GM13 stamped inside the head. I saw that it is Mexican built, is that good or bad? How can I find out if it is a earlier or later model block and whether it is a roller motor or not?

 

You could ask the guy.... It's pretty obvious if it's a roller block, it'll have the tappet holes in the lifter valley.
If in doubt? Assume the worst. It's a 1977 hencho en mexico block, with 993 or equivalent heads.
The block is ok to use, the heads are junk. Just assume that and move on...