You have what appears to be a 1969 SG Special
It has the 3 piece neck, which is stiffer than the 1 piece neck, no volute, no "Made in USA" stamp.
The Gibson logo also has no dot over the "i", and the "o" is open like a "u".
I have a 1969 SG Standard with similar features.
I also have a 1968 SG Special with the same Kluson tuners that yours would have had originally.
Here's a picture of my '68 Special- yours would have had the same Kluson tuners.
You are also missing the bushings that fit on the front of the peghead.
Even though you have chrome hardware, the tuners would have been nickle plated, as is the case on mine.
You can get reproduction Kluson tuners that look like the originals and say Kluson Deluxe on them, although in 1 row, unlike mine which has 2 rows, but yours might have had the 1 row anyway.
You can get a set of tuners, with bushings and screws, on ebay, for a very nice price from this guy:
Tuners
Disregard what the caption says- they are the right ones.
The only problem that you may have is if the holes have been enlarged for the tuners that are on it.
If they have been enlarged to 3/8", which was common, you need conversion bushings like these:
Conversion Bushings
Your peghead does not appear to have been drilled, but you can never tell until you measure it.
As for the Vibrola arm, they are the same for Specials, Standards and Juniors.
This guy sells a very good reproduction for a good price.
Vibrola Arm
You can watch ebay and try to find original tuners, but they were usually taken off for a reason, or are very worn.
I have reproduction Kluson tuners on my 1969 Standard and have had no trouble with them.
You might be able to find a vintage Vibrola arm, but you'll pay big money for it, and they usually don't look much different than the reproduction arm unless they're beat up, and your SG is too nice for a beat up arm.
Also, your fretboard needs oiling.
Fret Doctor is the best fretboard oil out there, available here:
Fret Doctor
When you're done, your SG Special will look like mine.