Since you don't have non stock amp draw items, the newer Alternator is OK. It will be OK, in my opinion to wire the ammeter. You are correct, you would not have a voltage reg with internally reg alt. SOoooooooooooooooooo keeping in mind AAW doesn't like ammeters and I don't either, I do understand that a stock look is best. Logic says if the ammeter was designed to read/handle loads in an original/stock truck, it will be OK. The alternator will only output what is necessary.
You WILL NOT find a way to install a volt gauge in the ammeter hole and have it look original or even good. unless you want to pay someone big bucks.
Look at pages 2 and 3 of instructions. Find the red wire from the mega fuse to the fuse panel. I believe the end at the fuse box is wired sort of permanent, so leave it terminated to fuse panel. You will cut it at the right place to do the following. Attach it to one terminal of the ammeter. Use the cut off piece for a wire from the other ammeter terminal to the Mega fuse. In other words, put the meter in series between the Mega fuse and the Fuse panel. Which terminal on the ammeter gets what wire you ask? If it's backwards, it will read backwards, then you switch wires.
It would be nice to test the gauge cluster before a tight "button up".
I actually like idiot lights for charge and oil.
Wire the other Mega Fuse wire as shown in the instructions. (starter to alt.).
Remove the alternator output wire from the mega fuse and place it on the same ammeter terminal as the wire to the fuse panel. FYI: The AAW diagram does not show that the battery positive cable is connected to the solenoid large stud.
