The version tested in occasion of November race in Hockenheim, with 1750 (Schultze) was decidedly not lightened, nor it was the GT 2000 shown in Tour de Corse, where the 2000 cc narrow head engine was tested for the first time.
I do not know if it is true or not, but I read that in 1968 s/n 613997 got 1905cc engine with two hydraulic chargers, dry sump, testa stretta head and monosleeve block. It had 315-325 HP at 7800rpm. It also received multilink suspension from TZ2. The weight of the car - 730 kg, max speed 270 km/h
The source was here. The original text is gone but I have a copy
I never got that SA2, but I did get to drive it at Autodelta's Balocco track.
Chiti told me the car weighed in at 730 kilos, and the engine output was between 315 and 325CV (depending on the compression ratio) @ 7800 rpm.
This GTAP/SA2 had a modified TZ independent rear suspension setup and the narrow head, mono sleeve dry sump motor. I seem to remember it had the guillotine injection intake, but I'm not sure of that fact.
It certainly was quite a car in both looks and engineering. Great handling, fantastic braking, and very, very quick, with no lag. I pegged it at 270 km/h.
It had the exact same plastica parts my GTAP has (doors, hood, deck, and Plexiglas windows all around), along with a most unique (for then) rear spoiler/deck that unfortunately, was non-operational on the day of my drive.
The plastica rear deck had two hydraulic cylinders attached to a metal frame molded into the deck that was supposed to raise the deck at speed (I have no idea how it was activated or engaged).
So in effect, it was an active aero wing system made to look like the stock GTA rear deck when at rest. Quite exotic and clever for its time.
That SA2 deck may have just been one of Chiti's many "gee whiz" designs that didn't actually work, but sure as hell really impressed everybody.
Carlo Chiti was quite the innovator and a real character as well. Had he let me purchase that car, it would still be around for race car enthusiasts to enjoy and marvel at. Yet another piece of Alfa racing history lost forever.
Update: I've since learned that this special "works project car" was chassis number 613997, and was a special one-off build by Alfa Romeo for Autodelta after the normal GTA production run was completed. It was built for FIA Gp 5.
The car was dismantled in 1969 and rebuilt as a NA 1.6L GTA/P. It was then used for the FIA Plastica parts Homologation as a "1970 Giulia GTA".
Supposedly, this car caught on fire at Autodelta in 1971. There is no further history attached to that chassis number from that point on that I know of.