How much mechanical ability do you have? Replacing the head gasket on a 5 is not an easy job, and if you have water in the oil, you prob have compromised the main & rod bearings. Water & oil on the bearings makes them wear out rapidly. Plus, if you take the head off (don't pull it UP, leave a corner bolt in loose and PIVOT the head on the dowell pin, that way you will not pull up the liners), if you don't, you will unseat the piston liner seals, then you have a whole new problem to deal with. If you really want to do this, you need to remove the cyl head, and then take it to a machine shop to check the straightness of the head mating surface, and possibly the block. Then hope that the liner seals are not compromised when you put it all back together...
Overheating Renault engines is unfortunatly quite expensive.
Sorry, I do not have the torques specs.