BBC do the 496
The 600 to 700 HP is a big spread. By that I mean you can do a regular pump gas BBC motor and make 600 to around 640. Now with E85 you can do more compression but street driving a tunnel ram around on the street is very cool looking but can be trouble some drivabilty wise.
I like the 496 idea, I like the intake runner sizes suggested, budget will govern which heads you use and opinions vary on that subjest also. I do like going with a roller valve train (but again a budget thing) get a custom grind ,Howard or comp will help you .
Good Luck alot of good info on this site
Welcome aboard