That looks a deffy chassis, did you post in the right section?
There is a firm that makes series's chassis's with coil sprung axle mounts, if its one of these before you fit it consider that to make it legal you'd need to sva the vehicle, a kind of super mot that you really wouldnt want to bother with, and on a classic may not be that desireable as leafs are a major part of the series.
I'm not saying dont so it though.