If this is a 396 I would pull the whole motor as is and then store it. I would replace it with a 496 (454 with an off shore stroker crank and bored 0.060" over) only I would look for a 496 based upon a rebuilt two piece Mark IV block. As to heads a set of oval port heads with 2.25" inch tuliped stainless swirl polished intake valves and 1.88" stainless steel exhaust valves with your hardened seats cut into the heads. I would also pocket port the heads and clean up any casting flash in the ports. You can also polish the exhaust port and clean them up (trim the valve guide and reduce the roof to gasket line) as big blocks are famous for their poor exhaust ports (and small valve size compared to displacement, and having good and bad ports, and a rotten combustion chamber shape: but some how gets the job done).
If it is a 396 I would retain the 396 decals, otherwise I would substitute some 390 horse 427 decals, as the 427 was only used in the Corvette and big cars, but rarely ever a 425 horse high performance version.
No one will ever know the difference (most can't tell them apart visually), but it makes a real seat of the pants improvement to go from a 396 to a 496. Unless some one is checking number no one but you and your machinist will ever know.