Kit comes with two light springs but you could just use 1 and keep the other 1 stock. That would speed it up a bit and should work good unless your compression is 10 to 1 or more.
I love my MSD, most folks said I was over doing it going with a 7 box but with my 6 box and holley HP dp I was getting a bog from the light if I floored it too fast. After getting the 7 al box and the HVC coil the bog was gone no matter how fast I floored it. Motor idles good cold too and never stalls even in 30 degree weather and the HP has no choke, with the 6 box it stall when cold now and then.
Mancini still has some MSD 7 al boxes with the black Mopar name on them. Believe they are like $333, not cheap and the 8251 coil is another $125 but I am so happy I got mine a few years ago. I never go back to the 6 box again unless it was a stock motor. MSD did stop making them and has a "better" 7 box now for $550, thats over doing it, IMO but I haven't use it either.