guys i need help...please. Ok so i got a 91' stang tht was a 4cyl but has been converted in a 8 cyl. i want to change the brakes in a 8 cyl. do all i need to shange is the spindle and rotors and calipurs?

and also i just got a performance transmission put in, and wow it makes me jerk like crazy, b4 i had it put in i had a tuneup done. now it feels liek i need a tuneup and it hasnt even been a month it jerks my rpms rev up and down (but only a little) how do i make it not jerk. i believe i have a 3:73 rear end idk if thts good enough or wht?