The missing pins are a bummer but surely not disastrous. Your gunsmith can surely turn these out although without a pattern it might be a bit hit and miss.The cocking indicator is not that important but I would wonder why it got bust in the first place. With a gun like yours I would go one step at a time, starting with the bore measurements. If that area is ok then the jointing, then the pins, and at that stage you should have a working gun.
The cosmetics can then follow at your leisure.