"The front and rear clips certainly fit better than they ever did back in the day. can anyone help with the detail regarding the rear of the front wheel arch not lining up with the leading edge of the sill ? Looks a bit odd... "
Just to add a bit more perspective: I built a monocoque and when I remove the sill covers, there is the same offset. The reason is that the front wheel arch continues to flow backwards as part of the sill panel and defines where the leading edge of the sill starts. When you remove the sill panel the line is interrupted and it appears as an offset. It means that the Alan Mann sill dimensions are likely to be same as the originals. Not sure I've explained that too well....