Solved -PJ587- G.S. 18/4 Prototipo 1974 by Gatti & Silvestri

[Paul Jaray]

what is this?
1 point for you.
(I should receive more info about in a couple of weeks)

[dzima1985]

Italian?

[Paul Jaray]

Sì!

[AlexFrance]

Is it a road-legal Ferrari with some sort of a "Le Mans-style" body?

[Paul Jaray]

Not a Ferrari, but road-legal.

[AlexFrance]

So it must be some kind of 'Ferrari-look-alike' replica?

The body shell could be a mix of Ferrari 512M/S and 712...

[Paul Jaray]

So it must be some kind of 'Ferrari-look-alike' replica?

The body shell could be a mix of Ferrari 512M/S and 712...

so far so good...

[Djetset]

Is the car not to full-size scale, meaning it's based around something like a Fiat 850?

[Paul Jaray]

Not that small actually.
Not based on a Fiat 850.

[AlexFrance]

So is it a kit car or a one-off?

[Paul Jaray]

It should be a one-off.
I'm going to receive more info soon.
What I know is make, model, year and few technical bits.

[Paul Jaray]

This car was meant for limited production.
The chassis is 15cm shorter than the original one.
It remained a one-off.
It was planned for different engines.
I'm looking for maker+model...I'll fill in the details later.

[Paul Jaray]

Part of the answer is available online (and quite easy to find  ) but a Pro has to provide a Professional answer.

[moltogatto]

it's a "special" built in the Reggio Emilia area in the early '70s by Gatti and Silvestri, powered by a tuned Fiat 132 engine with a bodywork reminiscent of the Ferrari 512M one. The duo had plans for a limited productions but, in the end, it remained a one-off

[Paul Jaray]

That's impressive!
You probably have a particular issue of a particular '74 magazine...I wonder how did you remember it was there!
I found this car for sale, in a 90s magazine with no details about. Further search gave me several pictures of it, some technical bits but still no info about its builder...but there was a reference in a certain magazine. I took that magazine and there was the answer!
I was sure someone would find the 'online' answer, but not the 'hidden' answer before!
Just to complete it, how was it called? It's not reported in the article but each site where it is (was?) for sale calls it that way.
Locked for you.

[moltogatto]

Italian weekly Autosprint reported about the car back in the '70s, I remember I saw it when, as a very young kid, used to avidly go through them every copy I could reach for some years ago I saw it again, when I got some late '60s/early '70s collections for my "archive"...car name should be G-S

[Paul Jaray]

Ok, nearly there but you got the point! 
I found an ad: G.S. 18/4 Prototipo 1974 in a magazine. Nothing more.
If you google those words (or just 'Ferrari 512m replica') you find the car for sale in different sites, but there's nothing more except that is Fiat-powered and few bits.
There is also written that this car is featured in just 1 magazine, Autosprint. I bought that magazine to have more info and there are the builders' names...
You have a very good memory, I was sure someone would find the G.S. 18\4 name but to complete the answer that magazine was crucial...and you found it right away!
A well deserved point for you!

[Paul Jaray]

As a very stange coincidence, this car was shown in Padua in the late October.
I was not aware of that and I found it in December in a circa 20-years old magazine.
This month, as Moltogatto pointed me out, it was featured in a magazine, 'Automobilismo d'Epoca' and after a quick search I found out that another magazine, Epoc'Auto, features this car in this month's edition.
Here you are those articles:

[dzima1985]

Grazie, Paul! 

[dzima1985]

G.S. at the Auto e Moto d'Epoca a Padova 2013