GM has an awesome warranty and it comes with great parts all at a premium price. Have you considered any other reuilds? Blueprint engines have a good rep and like someone said above, no more expensive to build a 454 than a 402 and anymore that is true with a 496 as well.
https://www.speedwaymotors.com/BlueP...ine,52469.html
Why not get a long block? ATK 454 for $2400.
https://sdparts.com/i-24075971-atk-d...iABEgLaMfD_BwE
One reality is that big block Chevy's are expensive. I just went through a 427 from a boat and spent WAY more than I wanted to, but that's the nature of the beast. Rebuilding stock cylinder heads one of the largest expenses.
I don't see any reason you can't pull it, check it, and then make the call. It may just need valve lapping, valve seals, ball hone and new rings and bearings.