Prince
Torque King
I'm not so sure, there are plenty of Track/Race 306's over on the GTI6 that have done this but I'm not sure if it's nessersary on a road car, I'd like a crack at doing it but getting suspension right is still a little out of my understanding.
They have used rear coilover suspension and the torsion bars are still in the tubes to keep the trailing arms in the beam, some have even talked about borrowing a rear subframe from a BMW Mini so they can have fully independant rear suspension.
The 306 Maxi rally car had torsion bars and that thing gave the big 4wd cars a run for the money on tarmac. Plus I'd be affraid of spoiling the personality of the car. (It's kind of why I choose it over a golf or a saxo.) I'd reckon though a rear set up from a 405 or 406 would be better maybe if it was to be done....
Still a lot to think about though as I do like smart engineering solutions.
I have no strut bracing what so ever at the moment.
If you plan on making it 'the best it can be' and keeping it then the conversion is probably the better option imo. I'm not familiar with the suspension on a 306, only the basic setup but surely you can't really do much with the rear suspension because of the torsion bars. At what sort of cost have the guys on GTI6 done the conversion?
Brace wise you should have the option of front upper, rear upper and rear lower. With yours being FWD I would definitely get a front upper to tighten things up.