I don't have a 1400, Clementine, the Plein Air replica has a 1108cc R5 engine.
Greek imported R4s are fitted with rear anti-roll bar and 16mm front one as standard. Their ride is rather stiff for a R4 (but not unpleasant). You put me thinking if wider tyres work best with this setup,or vice versa...we have all possible combinations here, plus Galaxian's R4 Safari which is of "special version" specification (567) and has F4 torsion bars! Maybe we should organize a comparative test...
If you can find DeCarbon-style shocks (now built by Delphi), go for them, they are gas-filled and perform very well, let's see now how long they will last...