The regulator has little to do with output and is the simplest part to change.

It's the rest of the charging system that needs replacing and upgrading. Wires, ammeter, fuse links and likely even belt and pulley arrangements like going to double belts.

I would think all you need is a Denso conversion. i know quite a few cars with just a 60-80 amp Denso alternator and they do fine even with big fuel pumps,fans and electric water pumps.
Gus

If those high draw items are powered directly off the alternator, you might get away with not upgrading the rest of the wiring. Better safe than sorry though.

What else needs upgraded? A load will only draw as much as it needs. For example, the tail lights are not going to take any more current than they did with the original alternator.

What ever additional high current loads that may be added would need appropriate sized wiring to handle those loads and some thought as to where to feed them from, but nothing stock is, assuming a good condition harness.

When I updated my 51 Plymouth to a 78A 12v alternator I used the battery side connection of the fender mounted starter solenoid as the tie point to feed my electric fan relays (24A draw on high) and to tie the output of the alternator to. The aftermarket gauge kit I am running has no ammeter so I didn't have to concern myself with that. The EFI feed comes from there too. The rest of the wiring harness is a generic 12v spec 21 circuit harness. When I get around to adding AC I will feed that relay from the same point.

As noted where you take the load from is important. But let's say something goes wrong with the battery, the alternator will power through the original wiring until it melts. Big problem. Especially with known weak points like the bulkhead connector.

I've seen too many rolling fire hazards, usually related to stereo systems.

I bought and used a Power master 100 Amp single wire alternator on my last street and drag race car, I ran an 8-gauge wire straight from the alternator to the positive post on the battery and added a volt gauge from the ignition side from the stock fuse box. I disconnected and didn't use any part of the original charging circuit, I did have to back feed from the battery back to the ignition switch to make the new alternator work in that 1971 Duster
As already mentioned, you can't safely run a lot more current, 80 Amps+, amperage, through the early low amperage stock factory wiring
IHThs
Mopar cars in 1969 had a bad reputation on the entire electrical system, many caught on fire and burnt to the ground due to the issues in the wiring

My amp guage is reads low at idle even when only supplyingpower just for fuelpump and motor. it gets worse as headlights or heat motor is used. it will go back up to charge when at about 1500 rpms. just concerned.

My amp guage is reads low at idle even when only supplyingpower just for fuelpump and motor. it gets worse as headlights or heat motor is used. it will go back up to charge when at about 1500 rpms. just concerned.