Alternator Amp test

Hey guys
I'm doing some work on my 68 barracuda.
It's a 383 S matching #. I have upgraded to MP electronic ignition and cracked back's headlight relay kit (that I still have to install) I want to leave the original amp meter (good idea ?) I bought a sunpro volt meter that I was going to convert and install in place of the amp meter in cluster but changed my mind.
Any way my question is..
Is there a way to test my current alternator to confirm the amp rating?
Can a alternator repair shop spin it up?
I want to leave the car as close to original as possible but want it to be safe..
The car has original radio.
Thanks for any advice.