Just incase anyone is interested i bought 197/200 master cylinder in the end from Renault, its goes on the 172/182 no probs at all. The only things you need to change are change the rear brake line fitting for M10 instead of M12 (200 cylinder has two M10 outlets instead of M10 front M12 rear on the 172 cylinder), wind the push rod out on the servo (doesnt have to be done but there will be more slack before the pedal acts on the M/C) and you have to use the brake resivoir seals from you 172 cylinder on the 200 one. Other than that its goes straight on,
Im yet to test it on the road yet but the pedal has less travel now and is much firmer which is what i was aiming for, feels more factory now.