I currently own a 1993 Chevy Caprice Police Package (9C1) . If I can remember right I think it has either a 120 or 140 AMP alt in it. The regular caprice had the 105 amp in it.
My previous car was a 1989 Caprice Police Package.
If your totally going to go to a higher alternator, you may look into a Ambulance Supply company. Alot of Ambulances and Fire Trucks run 200 + amp Motorola alternators.
They might be on the expensive side, so be forewarned.
I am not a mechanic, but also keep in mind that serpintine belt upgarade may be in need here. I could also imagine the amount of horsepower the bigger alterntor will rob form the engine. If your not worried about performance, then skip the horsepower thing
You may want to go the route of a second battery and a RV battery isolator. I know they sell battery isolators in diff amp ratings, might wanna get one of at least 100 AMP. Also keep in mind cable size...etc to be able to handle the higher charge current to the second battery.
This way you run your amp power to the second battery. The isolater ensures only the second battery is used for the amp, and the main battery used for the vehicle. There is room under your hood for a second battery, just move the fuel canister behind the headlight. Or you could run some massive gauge copper cable from the front to the trunk area and mount your battery there...but...the collection of battery fumes may not be a good thing
But now you gotta figure, just about any way you go is going to cost a few bucks. Why not just run barefoot with 100 Watts
Another thing I just thought of, and to watch for. The Caprice alternators can be prone to noise under high loads. Back when I was a dispatcher for Frederick City Police Maryland, you could tell which officer was driving a Caprice. When they made traffic stops they would key up and call in the tag, vehicle description...etc, it would put some noticeable whine on the radio. Running a 100 Watt Motorola Micor UHF radio, running the Federal Jetsonic light bar, dash light, halogen flashers...etc, it put a killer load on the alt and would whine. Only would wine under a huge load, otherwise ok.
Also, something else.
An option on the Police package was a bonding strap kit. GM bonded the hood, turnk and front and back bumpers to keep down RFI and have good grounding....just a thought.
Anyways, just a few suggestions
Experiment at your own risk