sounds like your having some problems, mate if it's giving you the shits just get rid of the peice of shit, like ya grandpa probably told you, stick on the stromberg, my email adress is mljulien@optusnet.com.au if you want to sell it.
if you decide to keep it i would suggest a commodore pedal, I have a VB-VL style pedal in mine wich replaced the HZ one I had before, if you buy a cable make sure it's gonna reach as the 6 cyl commodore cable is usually to short so try to get a V8 cable, V8 stuff goes faster too, i believe the 390 is more suited to a holden 6 than a 350 becuase the 350 is to big for power low down so if some one tells you to get a 350 instead tell them to shut up.