. OK... Forget swapping pistons or rings... forget collapsed rings, whatever the hell that is... forget swapping springs..
. You simply have the lash adjusted wrong on #2 and maybe partially wrong on another one... as Eric said, you have the exact symptoms of misadjusted valve lash... engine won't run at low RPMs because #2 is exhausting fire into the intake manifold mixture via a held open intake valve, which is messing up all the cylinders... (one way to find correct TDC is watch the lifters for the cylinder you are adjusting and make sure neither one is in up position at all... not in the slightest...)
. Before the valves are adjusted, the valves all stay closed, and you will, thus, feel pressure in the cylinder on both the wrong and correct TDC rotation of the crankshaft, which confused you... simply need to get #2 on the correct rotation and adjust the valves... same for any other cylinder which isn't exactly correct... you can do it... you got 6 1/2 or 7 of them correct (with prolly some luck on a couple)... you can finish it... if you don't understand anything I wrote, just ask some more...
. 1 turn lifter pre-load is correct, so is 1/2 turn, so is 1/4 turn, so is 1/8 turn... they're ALL correct... nobody was 'wrong'... it just depends on what you're doing... I use 1 full turn (as does the factory) on a slow revving stock engine with a stock cam so the lifters will prolly never need to be adjusted again despite normal wear... which is one of the reasons we went from solid lifters to hydraulics... on a bit of a performance cam, we use 1/2 turn to limit amount the lifter can pump up, prevent valve to piston hitting, and speed its recovery from pumpup if engine is overrevved... on higher performance engines, we may go 1/4 or 1/8 turn for MORE of the same reasons... however, as go less than 1 full turn, more and more likelihood that normal wear will cause lifters to eventually start clicking and need the dreaded re-adjusting...
. BTW, don't know what HP was claimed for your engine, but a SBC 350" can make up to 300HP on the stock/standard/basic cam (~194/~202 durations)... above that a performance cam (GM option or aftermarket) of some sort needed... although some poorly designed 350's, such as GM Mexican crate engines, use a big cam and yet still under 300 HP...