'Cuda alternator questions

Hi everyone, I have done a few searches under different phrases and can not locate a thread to help with following:
1) Where can I find the specs for the original alternator for my 66 273;
2) I want to upgrade to a higher output alternator due to additional accessories (sound system, etc - car is being re-wired front to back w better wire, eliminating ammeter, and firewall connectors). I have heard that the standard alt is 37A or 60A, but nothing definitive. My estimate is that I will need around 75A to 90A.
3) for such an upgraded alternator, can anyone suggest a good source(s)?
4) is there anything I need to know when upgrading to keep from doing any damage?

Thanks for your input :)