Skeleton rack verses reversible panels often came down to personal preference when new.
You received a verrrrrrrrrry good price for the complete '66 deck, including seats. I've seen reversible panels in great shape and others that became misaligned and caddywompus after being in use for a few years. Factor this into consideration: Can you have a skeleton rack made for less than the total cost (including labor) to supplant the '66 parts into your '70? Likelihood of finding a skeleton rack is, well...abysmal.
You can always add just the jump seats if deciding to go with a skeleton rack. If you buy the '66 parts, be sure to take moldings that go around floor openings for panels and jump seat area. Dependent on make, there may be a lower floor molding around jump seats as well. What make is the donor?