R3 Block Unfinished- CO

We are still trying to figure out what this block actually is. So far it is a 59* Block "Lifters are close to the Valley Wall" with 360 Mains and not 340's, one mounting point of the ears on each side of the block has been machined half way off. The only numbers on the block are P4532907 which is a casting number. If you research that number you will see that there are several variations of part numbers that would identify what this block actually is "Bore, Main Sizing, Deck Height, Cam Journal Size, Siamese Bore or not etc. On one of the mains there is 4532648 stamped on it. The seller and I have done all kinds of searching but come up blank on all particulars of this block. If anyone knows different on what this block actually is, please chime in and help if you can. If you know where to find the actual part number markings on this block to help identify it that would help too.