In Curami's book, 'La Sport e i suoi Artigiani', there are 4 pages about Conrer's sports.
There is a pic of the puzzle's car and Virgilio Conrero: 'Virgilio Conrero next to his Conrero 2000 of 1959. The car never raced at the time'
There is also a long story of the 2 versions of it:
few minutes for sum up...unless you are looking for 'Corna'...
I'll add the pics if possible
The 1st:
In 1953 Conrero made his 1st sport, with an Alfa 1900 Sprint engine, 130cv, chassis by Savonuzzi and body by Ghia.
In 1954 the same car was rebuilt according to a design by Koren and raced the Mille Miglia.
In 1954 was again rebuilt by Michelotti and raced the Sassi-Superga.
In 1955 it raced the Grand Prix des Frontieres as 'Alfa Romeo Speciale' (#36) with a 160cv, 1975cc AR1900SS engine.
In 1956 it entered the Aosta-Gran San Bernardo as 'Conrero 2000' and 173cv.
The 2nd:
In 1959, a similar engine with a desmodronic engine was fitted on the Conrero Sport presented in 1959, based on a Osca Mt4 chassis, designed by Michelotti and built by Canta, but it never race.
The car #2 should be the puzzle car.
There is a 3rd Sport, built in 1959, that is the one in your reply #24...here the story:
I would tend to agree that the puzzle is car #2 but proving it is a different matter.
In my book "Osca - La Rivincita dei Maserati" by Luigi Orsini & Franco Zagari there is no mention of which Osca MT4 chassis the car may have been based on.
The book is extremely detailed on every Osca chassis - types, years, owners, etc. and if it was possible to find the MT4 chassis no. this car was based on it may reveal the origins of the car.
It may have been a damaged chassis or one that had disappeared before 1959 when the puzzle car appeared.
Difficult but not impossible to solve.......