sounds a little like my car ;-)
I've still got the old heater cable and control, but am in the process of freeing it as it was stuck solid and a brass tap had been used in its place. I have a new control valve ready to fit. I know it may not be as reliable, but I want to be able to turn the heat off, I left the old brass tap open for a while but in this heat it was just too much inside the car.
I also have alternator and negative earth conversion, in which case the regulator is not needed and esentially used as a terminal block so it has been removed in my car. and its a mess that I need to resolve at some point.
here you can see how I got her....
You can see the heater cable has simply been tucked under the bracket for the air intake and has rusted soild at the end.
The regulator has replaced by some sort of fuse box, although only the two main fuses should be needed (plus one inline for the side lights I think?), some one correct me if I'm wrong?
I've already removed the tow-electrics warning mess at the top (tow bar comes off soon) and replaced the flasher unit for a new one as the old one was failing. Next step is to tidy up all those joints, find a fuse box cover and consider removing the mess where the regulator would be (might be easier to buy a 'dead' regulator and use it as a terminal block it would look more original too).