Batt gauge headaches!

[67chevemall]

hello

I'm trying to hook up my batt gauge. I have the starter wire and
another smaller wire coming off the batt.
Now I think it is a ampmeter that is the OEM gauge so the
book says to run a wire from where the small wire from the
batt feeds the volt reg, then run that to the gauge and back to the reg.

Now that small wire off the batt is a 12g wire and the wire going to the
cluster plug is like 16 or 18 g and the printed circut is less then that.
Won't this cause a melt down? Do you by-pass the printed circut and
the cluster plug in and go right to the factory gauge? If so how did the
factory have it hooked up?

How the heck do you hook this thing up?