I want to eliminate a generator and voltage reg to install an alternator in my 62 Impala?

as long as your going with an external volt meter then you can disregard the old wiring at the regulator...that is if your using a internally regulated alternator. you should have a main charge wire [off the back of your alternator] & 2 small terminal,s...one marked F1 & the other marked F2. the F1 is the field charge terminal which only need,s a momentary flash charge to energise the field...it will then produce a back charge that must be addressed...originally G.M. used a resistor to solve this. you can do the same but I would use a diode instead [ allowing a charge in but not out] this would be installed in the field [ F1] wire before the alternator. use the F2 wire to feed your voltmeter. & of coarse hook the main charge wire to your positive terminal. if your still using the old style solenoid [ with one main terminal & 2 small one,s] then you can feed the ignition from there rather than from the ignition switch. just make sure you use the terminal marked with a "I" for ignition...best of luck!