Questions on a 512 block?
 

I may have found a 69 big block casting # 3963512 with 4 bolt mains and square port heads/intake and dimple rods(so he says). What engine could this be other than an L72 427/425 or an L88?

Re: Questions on a 512 block?
 

Get the two[or three] letter suffix on the engine pad. That will tell you exactly the application, or, whether it was a replacement block. If from a Corvette, it could also have been an L71 tripower 427. If it's a late '69, it could be an LS6. Although it could have been changed, see if it's internally, or, externally balanced. That will tell you if it is a 427 or 454.

Re: Questions on a 512 block?
 

I'm assuming the codes are missing from the deck of the block. I guess it would depend on the casting date and if it has a partial VIN stamped in it to really know what it is if the engine codes are gone.

Re: Questions on a 512 block?
 

Check out the rods (bolts). Correct me if I'm wrong, but I believe the L-88/LS-6 got the 7/16" rods while the L-71/L-72 got the 3/8".