TTI headers

i just ordered up the whole setup through hemidenny . step headers n full length exhaust for my swap over to 340 6pk in my 273 4spd 64 cuda . 8 3/4 already in , got cool suspension parts k/h disc's . just need a clutch to handle 400+horses with a 10'' disc . maybe a double disc setup . any one done been there n done that do's n don'ts yet ?