A good upholstery shop should be able to do minor repairs to the seat frames/springs, as well as recover in original materials.
As far as "modernizing" the seat to recline and go up and down. It would take a lot more than the 1K budget you have.
You're best bet if you want modern seats and don't care about the originality or look is to find a late model car or truck seat that has the power options you want...and then the fun begins trying to adapt them into the Bird's interior.
