I didn't know that the offset was called 'ET'
I suggest a trial fit and check for clearance to the strut, and to the gearbox end housing on full-right steering lock.
185/60/13 just fitted on my Uno Turbo but rubbed the gearbox slightly.
As for 'low profiles' for 13 x 6" rims... technically anything lower than 82 percent (no number, e.g. 155 13s) is 'low profile'

But that is by the standards of the 1970s. I suggest the 175/60 13s if you can find them... but 185/60 is a good enough substitute. I have 195/45 15s on my Uno Turbo and I guess you'd call them 'low-profile', but I still have the same gearbox rubbing issue and it makes ****-all difference to the car's capabilities anyway, it's mostly for looks. It makes a bigger difference if you buy good quality tyres rather than 'budget' tyres.
Yes, I did type asterisks there...
Maybe I'm getting a bit tyred of the high-claims for low-profiles, since I have 215/45/17s on the Stilo (the standard size!) and they're a bad choice for ride quality, steering feel etc. They probably cost as much for one tyre as for a whole set of more 'normal' tyres!
-Alex