1969 BB Ident. Question

[Seattle Sam]

I visited a friend yesterday who recently bought a 1969 RS car, painted metallic grey with a black custom bucket interior. This car came with a built-up 350 in it, and a turbo 400 trans. He was wondering if it could be an SS car...

I found the following things when looking at his car:

RS badge in front grill (positioned high, and held on with the curved oblong metal "push nuts")
12-bolt rear
four-leaf springs
brake proportioning valve under driver's door (on subframe)
big block heater core cover
big block fan shroud
3/8 inch fuel line with return line (return line did not get hooked up to the small block engine, it is just sitting there open with no cap on it)

We did not jack the car up to look for a VIN on the turbo 400 nor get the rear axle code.

This car looks to me to be a big block SS car, am I mistaken? Is it true that Van Nuys did not use "X" codes? According to CRG, turbo 400s were used only on big block cars. If this is true, then a VIN on that trans would be good evidence. Where do I look on the turbo 400 for the VIN stamp? Are there any other items I can check that could reassure one way or the other?

Here is the cowl tag and VIN info for the car..

ST 69 12437 VN278865 BDY (1969 Camaro sport coupe built in Los Angeles (Van Nuys))
712 52 B PNT (black custom interior, garnet red, black vinyl roof)
02D S128 (Fourth week of February, LOS code meaning unknown)

and the VIN is 124379L525xxx (Camaro V8 sport coupe 1969 Los Angeles)

Thanks in advance for any help....
-Sam