Yes! Some conditions, such as slipping generator belts or shorted-cell batteries could throw off the interpretation made by voltmeter readings alone. A temperature-inspired alternator diode opening up or stator winding shorting could be missed relying on a voltmeter alone, just as the state of charge is difficult to guess by ammeter alone.

Both would be best, if you have the room, and can accommodate them safely.

Regarding how to wire it, I don't know if the 1800 suffers from the same challenge the 240 does: In the 240, the alternator and starter are part of the same mechanical assembly, vibration-wise. So the wire from alternator to battery connects at the starter. That leaves only the starter cable to the battery needing flexibility, high strand count, and safe mounting.

To add an ammeter requires a second large-capacity wiring between engine and chassis, along with its requisite care and attention to safety over time, temperature, and repeated flexing. And then, the shunt ammeter is the only practical safe way to get this information into the cabin.
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Art Benstein near Baltimore

Every calendar's days are numbered.