Robert's price estimates are accurate for the shops here in so cal that are trustworthy. His estimation of all the unknowns is something only you can answer. If your rebuild candidate is a rusted, leaky, hulk....well maybe a good used runner is the way to go.
One thing to consider is the heads on your '69. If they don't have the air injection humps, that's a plus. Pop on a IHOnly aluminum 4 bbl manifold, a little cam, and you're gonna have a rockin' little motor.
Show us the pics of what you end up doing!