Rebuilt ‘77 440

Not an RV/industrial block.....at least it's not a 440-3 block. Some van RV's had the 440-1 block. I can't tell from your photos if the heads are for the 440-1 or-3 block. The 452 casting heads for a 440-3 block used the tapered seat peanut plugs, the 440-1 heads use the 13/16 gasket plugs like all the cars used.