I haven't done it myself but I'd like to. I'm doing a C4 dana 44 rear now but if it's not up to par I think I'm going for the 5 link. Originally it's a riley&scott thing, based on Jaguar stuff. It's hands dowbn the best out there for the C3.
BTW, I may know someone who has a pre 80 5 link for sale, including coil-overs.