Check to see if that block has a place on each side for a dipstick. If it does, I wouldn't put more than a max of 550 to 600 hp to it if using a stoke stroke crank. If you want to stroke it to a 3.75 that would still be ok.
If it has only one dipstick hole it is more likely to be a USA made block and with all the previous included but with using a main cap girdle or 4-bolt or splayed caps and a block half fill with Hard Blok and fully prepped the block should be able to take 850 hp.
The SB Chevy block is one of the strongest factory SB engines there is, IF it is not made in Mexico or is a Target Block, also made in Mexico.
Warning:
I do not like aftermarket cast steel crankshafts. Factory cast iron is as good if not better. Factory nodular iron 400 SB Chevy cranks are killer and will handle anything your block can.
Ed