I currently have a 38 amp alternator and would like to upgrade. Going to run a new radio and 6x9's speakers, nothing to big. Maybe an ac later, can somene help me with what i need. My engine is a 302 and i dont want to spend big bucks. Would like a 60 or 70 amp
You can get 1G alternators (like your existing one) in amperages up to 100. 75A would probably be plenty. No special wiring, etc., needed, but if you go over 75A I'd recommend upgrading your alternator BAT to solenoid wire to a heavier gauge just to be on the safe side.
You can also do the 3G route as described above. These are internally regulated alternators and you need to adapt them to the vehicle harness as they eliminate your existing external voltage regulator.