help with transmission choice

I have a 1984 mustang that is getting about a 500 hp bbf put in it. Will a stock c4 with a shift kit take the punishment or should I use a c6.

i've had both with no problems,but a c6 would be better for heaver street duty.if its not too heavy and a track only kinda ride the c4 would be ok.c6 is a little heavier but lots stronger and both are same ratios,2.46-1.46.