it's not so much about the hassle, it's about the money to make that kind of power (from that starting point) and do so reliably.
if you're talking budget and stages of upgrades i'd say 5.9 from the yard is probably the easy and dirty way to make it happen. or start with a 360, or maybe that 340 block. those will give you the broadest selection of aftermarket go fast goodies both new and used.
is the rest of the car sorted? like, chassis wise? because that's a huge financial consideration as well.