I've got the build info at home, so I'll check later tonight. Yes the rubber boot is like the inside one on the 69's. They're definitely not rear belts placed in front. I have two 67 Camaros both originally with Deluxe gold interior. I'm restifying the other car and changing the interior to black. I pulled the rear belts out of it recently and they are not the same.
I'm 100% sure the belts on the RS are original. Its a documented 2 owner car (prior to me) and its dead stock, although the previous owner did replace the seat covers and door panels because they were fading.
One thing to also note, the console doesn't have the clips for "resting" inside belts. Nor are there any holes from where they might have been.
I took this pic a while ago, but you can just make out the belt retracted.
