'Cuda alternator questions

I think stock was ~30 A. There were round-back alternators rated 60 A, mostly for taxi and other fleets and most/all had the "fleet bypass" of separate wires thru the bulkhead and perhaps a bigger ammeter (?). A popular after-market upgrade was stator coils for ~60 A from J.C. Whitney, so yours could have that. The later square-back alternator is rated ~50-70 A and, more importantly, puts out more current at idle.

How did you determine the current you need? I think the current ratings on many things like fans and amplifiers is "worst case" and their average draw is much less. Peak loads are supplied by the battery. The alternator just needs to provide slightly more than the average load to slowly recharge the battery.