Justo, you mean a FIAT A-38.. no way, too late, by early 1941 the A-38 was in the dustbin (except for its cylinders banks, but this is another story..). Having triple checked, I can offer a theory:
Since the drawing was a conceptual design, not a project drawing, it could be simply wrong in details. As you may notice, the fuselage of the Re-2005T-Axial is rather different form the regular one (I attach an inboard profile for comparison). The rear is longer to make room to the burner tube, but all the mid-to front section has been reworked too, to make room for the compressor and the power transmission complex. I checked with the forms of all the inline inverted-V engines (I think there's no doubt it is an inverted V) in use or in construction/project in Italy by 1943. No one was similar. The rear section is DB-605-like (compressor skewed from down-up), while, for example the Re-10X M-engine had a vertical compressor installation. The 603 is 605-like, and I don't think, for other reasons, it is a 603 (the R projects was initiated just to have a high-performance interceptor BEFORE the 603 would have been available in quantity in licence-build version, in second half of the 1944). In case you noticed what I said on the Gamma used for the static test of the idea, the IF V-engine were all upright-Vs, or impossible to use (air-cooled).