I'm putting a BB 454 in a original 6 cyl car. I need some ideas on some springs because im sure the original springs that were used will not handle the extra weight. Thanks!

the stiffer factory springs would work nice, if you're not going to drop the car;
moog 5662 or moog 5664 (stiffest).

I just need stiffer ones so it wont sit too low. Thanks! & where can i get these springs?

NAPA, or most good parts stores, Just give them the moog part number that Sonix listed.