68 valiant signet

as you may have seen i've fitted an explorer axle to my valiant. the parking brake is all but useless. i welded the looped end from the ford cables to the A body cables so they hook up to the parking brake levers and that all works fine. the problem is there is virtually no effort, which wouldn't be an issue if i hadn't converted my car to manual trans' also. so i need a parking brake that works. my car has the 'umbrella' type handle under the dash, i'm wondering if i'm not getting enough leverage ratio on it to make the effort it should. i'm not against fitting a tunnel mounted lever from another car as it's a driver/modified already so....
anyone come across this and how did you fix it?
cheers, neil.