Magnum Alternator Wiring
The amperage capability of the alternator is not the only consideration.
If you properly connect the alternator and have a suitable size output cable between the alternator and battery positive post, you can still end up with another meltdown due to existing car issues, like the amp meter in the dash.
Bypass the amp meter as others have suggested, and make sure whatever alternator you run has a clean ground path back to battery negative post, and make sure the alternator output wire is upgraded.