Well, Yes...it is a factory 4-Bolt main block. The hi-perf is there. The date code on the back of the block is
"K..4....9"

The best part is that it has already been Pressure checked and mag'd...Guy I got it from said it was out of a vette from years ago, been sitting for 20+ years and by the looks of the water jackets I'd say it hasnt been used since. The crank bearings were all GM std. on both mains and rods. The crank is a steel piece and the only # I could find on it was "7115". There are a couple of Delta triangle images stamped into the front countrweight and also an "X2614" stamped in that area as well.