[Super73]

I am sorry to say but I think that a 2k rpm converter paired with a 600-700hp BBC is going to be a turd out of the hole. My guess is the cam you will need to get you to your gos ls will move tq peak much higher in the rpm band.

Also, 600-700 n.a. is a pretty big nut to crack with out really thinking things out.

Being I know nothing about 781 heads, mind sharing what they flow? Hp is in the heads, don't skimp there.