generator alternator swap

Hi Guys and Girls



I am changing the generator on my 58 Sprite to an alternator, I need more
eremitical power I think the stereo drains it (Frank do you think the lag in
pick up could be due to this),



I have acquired an alternator from a 1972 - 1980 car. The problems are



  1.. When driving with the lights and stereo on lack of power and the batter
goes flat
  2.. Do I need a new bracket for the installation
  3.. Do I need to change it to negative ground and how
  4.. Will it make a deference