I know the SunPro volt gauge will not fit in that early A-body housing. I assume all aftermarket volt gauges are about the same. I can't help. A ford truck forum might have help with that one.
Slightly off topic, I have a '64 Valiant stick shift. I believe the auto trans models used the space next to the wiper and light switch for shifter control. Is there room to put a pair of gauges in that panel?