It’s been a long journey for you on this restoration of your Dad’s car.
I can’t help but think the shop knows that since it’s so close to the finish line now they are dinging you for ‘extras’ to keep the bill going before you actually pick it up. And since it’s so close to being done they are playing on your emotions to ‘just get it done so I can pick it up already’ which allows them to keep adding things to the bill.
If the meter is still running at the shop, I’d suggest picking the car up as is, paying for what they’ve done, and complete the rest on your own with the help of folks here.