The rear badge is from a Fiat 124 Special (saloon), 1438cc OHV engine.
The cylinder head and carb appear to be from a 124 Special also. (the 124 Abarth head would have been a twin ohc).
The 2 gauges appear to be aftermarket i.e. accessories (the Abarth rev counter would have been in the instrument panel).
I'm not sure what the steering wheel is from, I don't think it's 124 Special as any I've seen had a chrome horn ring between the centre and the rim, same as the standard 124 Saloon.
What is the red covered book on the right of the picture showing the handbooks etc.?
Al.