I'd like to see the 350 make 400hp or so with just a cam and springs. The 350 in it's day was an awesome motor and for certain applications it still is, but to make the 400hp mark with a stock bore not very worked over 350 is unheard of. Advancements in design and cyl head flow are what ultimately doomed the 350. Yes you can get a worked over 350 to compete with a stock LS. But it takes a lot more work to get to that point.
I am shelving my 350 to swap in a LS for one simple fact, my truck is 26 almost 27yrs old. It's got an antiquated EFI system on it, it has 180k miles on a very well worn 350 and on a good day made 210hp at most. The LS I am swapping in while yes displacement wise it is 27 CI smaller it pushes out 270-295hp/315-335ftlbs in stock form, and with the mods I am planning I will see in NA form ~450hp/475ftlbs, Boosting it (Turbo) i'll see 600-700hp give or take. You cannot do that on a 350 as cheap as the LS. I think all in all in NA form I will have ~$2500 into the complete swap which includes trans (Th400), converter (3000stall), Cam (BTR Turbo Stg3), Valvetrain(BTR), Tuning(either myself or a local guy).
The LS is far from gutless. At this point stock for stock it is the 350 that will get walked.