My thinking is if you're on a tight budget --- you build what you can afford and maybe start with a bit less... and "get 'er done". So many builds start off so aggressive -- but they're still sitting in garages and shops waiting for $$.... what's the fun in that? By the time you get finished -- it's old skool.
Just my .02 worth
My buddy is having a custom built 496 BBC - Brodix heads - roller cam - roller rockers - Long block and will be in it with taxes out the door $7500 including buying every single part including the block. The builder figures 600 TQ and 575 or so HP at low/street RPMs
Ever driven anything with 600 pounds of TQ? That will fry the tires as long as you want to hold your foot down...