cam question

so if i go to diff gears what whould b the best,and what year can i get the 8 3/4 rear end? like i said i dont want an all out race car just something kids can watch at track,i just wanna get little more power out off it,i took out powerstering,wipermotor,heater ****,all int out have two seats in it rest is gone,trying to take much weight out as can.I wanted to run exhaust out side of car, will that change anything?right now it comes off header into h pipe then muff then straight threw,i wanted to stay with same size is now just cut it off before wheel