Just got a 454 back from the machine shop today and can't tell what it is. It was commisioned and built for the previous owner, and came with the Elky that I'm working on and was previously in use in a '70 convertible. Its been with them a few years and was already paid for, I just had to get it from them and they can't remember anyhting about it. The front pad is blank, casting # on rear appears to be 861858 or 958, also says GM 10 T and date is I 22 77. The rear flange of the crank has an 839 stamped into it. Its got a fresh set of 702 heads on it and flattop pistons. I draw a blank on the block with Mortec, so any help is appreciated. It is a short deck pass block not a tall deck, I already measured. Thanks!

If the casting number ends in 959, it's a 454....

Dave,
If the number is 361959, it's a 454 made in 1978 thru 1987.

http://www.roadsters.com/bbc/#blocks

Bill, Tony, thats probably it, with a late '77 casting date. Thanks! Now to get it in!