Deano,
Those little Wilwood parking brakes are notoriously, uh... not so good. There are some modifications that you can make to the existing brake that will help a bit. I don't recall all the specifics but if you are an SCOF member (
www.performanceunlimited.com/scof/). There is a tech library there with this and all sorts of other useful information.
SPF has upgraded this brake to a small disk brake that mounts on the differential yoke and you can purchase one from an SPF dealer. It's far better and I think that's the way to go if you can.
John
spf1421