Adey
Just read this through. You have learnt a lot the hard way, but that is always the best way (ask me how I know sometime). Suspension: Get it up off the stops and use much higher spring rates and shortened stops, this will give you the look you desire, but will be much safer, and fun to drive, without damaging your fillings. Brakes have 2 options, either (1) use Dauph G front hubs which have R8 discs and calipers, or ( 2 and this is much more involved) Fit the R8 front suspension. The stumbling block here is your front crossmember, being a '57 it has a Dauph only crossmember, later cars have a Dauph/R8 crossmember which is only missing the pivot tube (easy enough to make and fit) My Proto is a '60 so it had the same crossmember as yours. I had a brand new R8/10 front crossmember in stock so chopped out the original and fitted it. It is not as big a task as you may think. Thinking aloud for a moment it is the hub that is the issue as chopping up a drum is not a great way to make a disc carrier (wrong metal) Dauph G hubs should fit the standard upright. I am not really the right person to ask about the older stuff as all I did was throw it all away and convert to R8/ bespoke bits. What are your longer term aspirations for the car? as that should dictate your course of action. As a general rule of thumb it is better to use later post '68 bits where ever possible as Renault had a major shake up of parts in general from steering column splines and front uprights to Crownwheel and pinion sizes in '68 and most things are stronger as a result. Top of that list is the sierra 5 bearing engine, which is not that strong really. It became the Cleon, which is for all practical purposes indestructable It may have been a better idea to have found a terminally rotten late 8 or 10 and stole all its oily bits as with a bit of imagination, luck and money (in that order) you could have a car with
potential for over 100hp and the ability to cruise at 80 effortlessly and I don't mean kilometers.
Happy Motoring