My guess is that it was an early 80's all nuevo record bike and that the RD and wheelset (including hubs) were replaced with available athena parts from the late 80's. Pretty much everyone racing in the late 80's ditched their original non-aero brake levers, diacomp levers transplanted on older bikes were a very common upgrade. Replacement of one of the rims was probably due to a damaged rim, do the hubs match? Original rim is likely the one with less brakepad wear on the sides. This mis-match of parts is pretty common for a nice bike of this age that was raced for several years after nuevo record was effectively obsolete. A racer on an aging bike would care more about keeping it reliable and updated with innovations like those cool new wave clipless LOOK pedals from 1986, care less about preserving it as an all original garage queen. Only odd feature I see on it is the 6-speed freewheel as those were very obsolete for racing by the late 80's and so easily replaced. The original owner (if they kept up with road racing) probably bought a complete new index shifting 8-speed replacement bike around 1990 and let this one languish like a time capsule snapshot.
Tubeset quality is probably best judged by the diameter of the seatpost, if 27.2mm it likely is columbus SL. If you flip it over, is there spiral rifling inside the steer tube?
If you want to restore it to original spec, I would go back to all Nuevo Rec parts.