I have seen some take out 496's for around $7500. If the truck engine was free, you would spend more than that for all of the accessories.

But he already has a big block so the accessories are there. And if he wanted EFI, I'd go new aftermarket. Most integrate everything and can self learn if OP doesn't want to do his own tune. Carbs are basic, but need a little attention to set up.
I feel a little comfortable with engines, so if it were me, I would take it apart, open the ring gaps. measure it off, repair any issues, and run it.
And if it's going to just go 3500 rpm all the time it could just bolt up and go.

I'm not sure his older Gen accessories will bolt onto a Gen 7 8.1 block? The 8.1/496 is a pretty unique platform. You might be opening up a real can of worms here.