The heat/AC switch was used up to the mid 80's they are available at the dealer/eBay

wipers, make sure the is a ground strap going to the motor and mounting bolts.

seat, they might of recovered it and didn't add foam. You'll have to remove the cover and ad some 3" thick foam from Michael's craft store or some place similar.

back up lights, make sure they are well grounded, fuse? bulbs?

As long as it charges when you rev it, it should be good.